LED driving apparatus and lighting apparatus including the same

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority and benefit of Korean Patent Application No. 10-2015-0091011 filed on Jun. 26, 2015, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to an LED driving apparatus and a lighting apparatus including the same.

Light emitting diodes (LEDs), generally described as semiconductor light emitting devices, may have advantages, such as relatively low power consumption, a relatively long lifespan, the implementation of light having various colors, and the like, as compared to existing light sources such as fluorescent and incandescent lamps. Based on the advantages as described above, the fields of application of LEDs have expanded to various lighting apparatuses, backlight units of display apparatuses, vehicle headlamps, and the like. In general, since LEDs may be operated by a constant current, an LED driving apparatus may include a rectifier circuit converting AC power into DC power and a converter circuit generating constant current power from an output of the rectifier circuit.

Recently, in order to reduce manufacturing costs by decreasing the amount of circuit components, as well as to increase reliability, LED driving apparatuses capable of driving LEDs without a converter circuit have been proposed. An LED driving apparatus having no converter circuit may include a controller integrated circuit (IC) having a plurality of switches and a plurality of LED arrays, light emission of which is controlled by the controller IC. The LED driving apparatus having no converter circuit may have advantages such as high reliability, low manufacturing costs, and the like, but due to limiting current properties of the controller IC, may be disadvantageous in that output of a drivable LED array is limited.

SUMMARY

An aspect of the present inventive concept may provide an LED driving apparatus capable of operating high output LEDs, simultaneously with driving the LEDs by AC power without a converter circuit, and a lighting apparatus including the same.

According to an aspect of the present inventive concept, a light emitting device driving apparatus may include: a rectifier circuit configured to rectify alternating current (AC) power to generate driving power for operating a plurality of light emitting diode (LED) arrays; a controller integrated circuit (IC) including a plurality of internal switches connected to respective output terminals of the plurality of LED arrays and configured to control a path of a current flowing in the plurality of LED arrays by adjusting operations of the plurality of internal switches according to a magnitude of the driving power; and a current controlling circuit connected to the output terminal of at least one of the plurality of LED arrays and configured to control a current flowing in the at least one LED array.

According to another aspect of the present inventive concept, a lighting apparatus may include: a light source including a plurality of light emitting diode (LED) arrays; a controller integrated circuit (IC) including a plurality of internal switches connected to respective output terminals of the plurality of LED arrays and configured to control a path of a current flowing in the plurality of LED arrays by adjusting operations of the plurality of internal switches according to a magnitude of the driving power; and a current controlling circuit connected to the output terminal of at least one of the plurality of LED arrays and configured to control a current flowing in the at least one LED array. According to yet another aspect, a lighting apparatus may include a rectifier circuit configured to rectify alternating current (AC) power to generate driving power for operating a plurality of light emitting device sets, each light emitting device set having an input terminal and output terminal and including one or more light emitting devices; a controller integrated circuit (IC) including a plurality of internal switches connected to respective output terminals of the plurality of light emitting device sets and configured to control a path of a current flowing in the plurality of light emitting device sets by adjusting operations of the plurality of internal switches according to a magnitude of the driving power; and a current controlling circuit connected to the output terminal of at least one of the plurality of light emitting device sets and configured to control a current flowing in the at least one light emitting device set. The light emitting device sets may be light emitting diode (LED) arrays.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the present inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram illustrating a lighting apparatus according to certain exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 3</figref> are circuit diagrams illustrating an LED driving apparatus according to certain exemplary embodiments of the present invention concept;

<figref idref="DRAWINGS">FIG. 4</figref> is a waveform diagram provided for describing the LED driving apparatus illustrated in <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 3</figref>, according to certain exemplary embodiments;

<figref idref="DRAWINGS">FIG. 5</figref> is a circuit diagram illustrating an LED driving apparatus according to certain exemplary embodiments of the present invention concept;

<figref idref="DRAWINGS">FIG. 6</figref> is a waveform diagram provided for describing the LED driving apparatus illustrated in <figref idref="DRAWINGS">FIG. 5</figref>, according to certain exemplary embodiments;

<figref idref="DRAWINGS">FIG. 7</figref> through <figref idref="DRAWINGS">FIG. 12</figref> are views illustrating semiconductor light emitting devices applicable to a lighting apparatus according to certain exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 13A</figref> and <figref idref="DRAWINGS">FIG. 13B</figref> are views schematically illustrating white light source modules applicable to a lighting apparatus according to certain exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 14</figref> is a CIE 1931 color space chromaticity diagram provided for describing operations of the white light source modules illustrated in <figref idref="DRAWINGS">FIG. 13A</figref> and <figref idref="DRAWINGS">FIG. 13B</figref>, according to certain exemplary embodiments;

<figref idref="DRAWINGS">FIG. 15</figref> is a view illustrating a wavelength conversion material applicable to a light source of a lighting apparatus according to certain exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 16</figref> through <figref idref="DRAWINGS">FIG. 24</figref> are views illustrating backlight units including the LED driving apparatus according to exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 25</figref> is a schematic, exploded perspective view of a display apparatus including the LED driving apparatus according to certain exemplary embodiments of the present inventive concept;

<figref idref="DRAWINGS">FIG. 26</figref> through <figref idref="DRAWINGS">FIG. 29</figref> are views each illustrating a lighting apparatus according to certain exemplary embodiments of the present inventive concept; and

<figref idref="DRAWINGS">FIG. 30</figref> through <figref idref="DRAWINGS">FIG. 32</figref> are schematic views, each illustrating a lighting network system according to certain exemplary embodiments of the present inventive concept.

DETAILED DESCRIPTION

Exemplary embodiments of the present inventive concept will now be described in detail with reference to the accompanying drawings.

The inventive concept may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. These example embodiments are just that—examples—and many implementations and variations are possible that do not require the details provided herein. It should also be emphasized that the disclosure provides details of alternative examples, but such listing of alternatives is not exhaustive. Furthermore, any consistency of detail between various examples should not be interpreted as requiring such detail—it is impracticable to list every possible variation for every feature described herein. The language of the claims should be referenced in determining the requirements of the invention.

In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. Though the different drawings show variations of exemplary embodiments, these drawings are not necessarily intended to be mutually exclusive from each other. Rather, as will be seen from the context of the detailed description below, certain features depicted and described in different drawings can be combined with other features from other drawings to result in various embodiments, when taking the drawings and their description as a whole into consideration.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items and may be abbreviated as “/”.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Unless the context indicates otherwise, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section, for example as a naming convention. Thus, a first element, component, region, layer or section discussed below in one section of the specification could be termed a second element, component, region, layer or section in another section of the specification or in the claims without departing from the teachings of the present invention. In addition, in certain cases, even if a term is not described using “first,” “second,” etc., in the specification, it may still be referred to as “first” or “second” in a claim in order to distinguish different claimed elements from each other.

It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element is referred to as being “connected” or “coupled” to or “on” another element, it can be directly connected or coupled to or on the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, or as “contacting” or “in contact with” another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).

Embodiments described herein will be described referring to plan views and/or cross-sectional views by way of ideal schematic views. Accordingly, the exemplary views may be modified depending on manufacturing technologies and/or tolerances. Therefore, the disclosed embodiments are not limited to those shown in the views, but include modifications in configuration formed on the basis of manufacturing processes. Therefore, regions exemplified in figures may have schematic properties, and shapes of regions shown in figures may exemplify specific shapes of regions of elements to which aspects of the invention are not limited.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Terms such as “same,” “equal,” “planar,” or “coplanar,” as used herein when referring to orientation, layout, location, shapes, sizes, amounts, or other measures do not necessarily mean an exactly identical orientation, layout, location, shape, size, amount, or other measure, but are intended to encompass nearly identical orientation, layout, location, shapes, sizes, amounts, or other measures within acceptable variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to reflect this meaning. Terms such as “exactly” or “identical” may be used to indicate no such variation.

Although corresponding plan views and/or perspective views of some cross-sectional view(s) may not be shown, the cross-sectional view(s) of device structures illustrated herein provide support for a plurality of device structures that extend along two different directions as would be illustrated in a plan view, and/or in three different directions as would be illustrated in a perspective view. The two different directions may or may not be orthogonal to each other. The three different directions may include a third direction that may be orthogonal to the two different directions. The plurality of device structures may be integrated in a same electronic device. For example, when a device structure (e.g., a diode structure or a transistor structure) is illustrated in a cross-sectional view, an electronic device may include a plurality of the device structures (e.g., diode structures or transistor structures), as would be illustrated by a plan view of the electronic device. The plurality of device structures may be arranged in an array and/or in a two-dimensional pattern.

As used herein, items described as being “electrically connected” are configured such that an electrical signal can be passed from one item to the other. Therefore, unless indicated otherwise, a passive electrically conductive component (e.g., a wire, pad, internal electrical line, etc.) physically connected to a passive electrically insulative component (e.g., a prepreg layer of a printed circuit board, an electrically insulative adhesive connecting two device, an electrically insulative underfill or mold layer, etc.) is not electrically connected to that component. Moreover, items that are “directly electrically connected,” to each other either contact each other or are electrically connected through one or more passive elements, such as, for example, wires, pads, internal electrical lines, through vias, etc. As such, directly electrically connected components do not include components electrically connected through active elements, such as transistors or diodes.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present application, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram illustrating a lighting apparatus according to an exemplary embodiment of the present inventive concept.

Referring to <figref idref="DRAWINGS">FIG. 1</figref>, a lighting apparatus <b>100</b> according to an exemplary embodiment of the present inventive concept may include an LED driving apparatus <b>110</b>, a light source <b>120</b>, and a power supply <b>130</b>. The power supply <b>130</b> may be a commercial power supply supplying alternating current (AC) power and for example, may output AC power of 220V-60 Hz. The light source <b>120</b> may include one or more LED arrays. In an exemplary embodiment, the light source <b>120</b> may include a plurality of LED arrays connected to each other in series or in parallel, and each of the plurality of LED arrays may include one or more LEDs.

The LED driving apparatus <b>110</b> may include a rectifying circuit <b>111</b>, a controller IC <b>112</b>, and a current controlling circuit <b>113</b>. The rectifying circuit <b>111</b> may full-wave rectify the AC power output by the power supply <b>130</b>, and may supply driving power to the light source <b>120</b>. By way of example, the rectifying circuit <b>111</b> may include a diode bridge. The controller IC <b>112</b> may control the LED array included in the light source <b>120</b> to be operated by the driving power output by the rectifying circuit <b>111</b>, and may be implemented as an integrated circuit (IC). The controller IC <b>112</b> may include a plurality of internal switches, and the plurality of internal switches may be respectively connected to output terminals of the plurality of LED arrays included in the light source <b>120</b>.

The current controlling circuit <b>113</b>, a circuit provided separately from the controller IC <b>112</b>, may include at least one switching element and a circuit element, such as a resistor or the like. When the current controlling circuit <b>113</b> is operated, a current flowing through the LED array included in the light source <b>120</b> may be dispersed into the controller IC <b>112</b> and the current controlling circuit <b>113</b>, and stress applied to the controller IC <b>112</b> may be reduced. Therefore, since a relatively high level of current may be applied to the LED array, a brighter lighting apparatus <b>100</b> may be implemented by including a high output LED in the light source <b>120</b>.

<figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 3</figref> are circuit diagrams illustrating an LED driving apparatus according to an exemplary embodiment of the present invention concept.

Referring to <figref idref="DRAWINGS">FIG. 2</figref>, an LED driving apparatus <b>210</b> according to an exemplary embodiment of the present inventive concept may include a rectifier circuit <b>211</b> implemented as a diode bridge, a controller IC <b>212</b>, a current controlling circuit <b>213</b>, a voltage detecting circuit <b>214</b>, and the like. An input terminal and an output terminal of the LED driving apparatus <b>210</b> may be connected to a power supply <b>230</b> and a light source <b>220</b>, respectively, and the light source <b>220</b> may include a plurality of LED arrays <b>221</b> to <b>224</b>. The embodiment of <figref idref="DRAWINGS">FIG. 2</figref> illustrates a case in which the plurality of LED arrays <b>221</b> to <b>224</b> are connected to one another in series within the light source <b>220</b>, but unlike the case of <figref idref="DRAWINGS">FIG. 2</figref>, at least some of the plurality of LED arrays <b>221</b> to <b>224</b> may be connected to each other in parallel. Also, it should be noted that <figref idref="DRAWINGS">FIG. 2</figref> illustrates a circuit configuration, and not necessarily a physical layout of the LED arrays <b>221</b> to <b>224</b>. For example, the LED arrays <b>221</b> to <b>224</b> may be arranged physically in a straight line configuration, but alternatively may be arranged indifferent configurations, such as circular, spherical, zig-zag, or other configurations.

As described above, the rectifier circuit <b>211</b> may be implemented as a diode bridge and may full-wave rectify AC power output by the power supply <b>230</b> to generate driving power for operating the plurality of LED arrays <b>221</b> to <b>224</b>. In certain embodiments, at least one of the LED arrays (e.g., <b>221</b> as depicted in <figref idref="DRAWINGS">FIG. 2</figref>) is directly electrically connected to the rectifier circuit <b>211</b>, and/or is connected to the rectifier circuit <b>211</b> without a converter circuit therebetween. A voltage of the driving power output by the rectifier circuit <b>211</b> may have a waveform repeatedly increased and decreased in a single period, and the controller IC <b>212</b> may control operations of a plurality of internal switches SW<b>1</b> to SW<b>4</b> on the basis of a voltage magnitude of the driving power detected by the voltage detecting circuit <b>214</b>, thereby determining whether or not to allow the plurality of LED arrays <b>221</b> to <b>224</b> to emit light. Hereinafter, a description will be made with reference to <figref idref="DRAWINGS">FIG. 4</figref>.

<figref idref="DRAWINGS">FIG. 4</figref> is a waveform diagram provided for describing the LED driving apparatus illustrated in <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 3</figref>. Referring to <figref idref="DRAWINGS">FIG. 4</figref>, driving power V_RECsupplied to the LED arrays <b>221</b> to <b>224</b> may have waveforms repeated in every predetermined cycle. In an exemplary embodiment, since driving power V_RECmay be generated by full-wave rectifying a commercial AC power of 220V-60 Hz, it may have a peak voltage of 220V and a frequency of 120 Hz.

Referring to <figref idref="DRAWINGS">FIG. 4</figref>, driving power V_RECmay include nine durations of t<b>1</b>-t<b>9</b> in a single cycle T<b>1</b>. Since a voltage magnitude of the driving power V_RECis relatively low in the first period t<b>1</b> and the ninth period t<b>9</b>, a voltage sufficient to emit light from the LED arrays <b>221</b> to <b>224</b> may not be supplied. Therefore, driving current I_LEDmay not be supplied to the LED arrays <b>221</b> to <b>224</b> in the first duration t<b>1</b> and the ninth duration t<b>9</b>.

In the second duration t<b>2</b> and the eighth duration t<b>8</b>, current I₁may be supplied to the LED array <b>221</b> by the driving power V_REC. The voltage of the driving power V_RECin the second duration t<b>2</b> and the eighth duration t<b>8</b> may be sufficient to drive the first LED array <b>221</b> but may be insufficient to drive the first and second LED arrays <b>221</b> and <b>222</b> together. Therefore, the controller IC <b>212</b> may set the current to flow through the first LED array <b>221</b> and the first internal switch SW<b>1</b> by turning only the first internal switch SW<b>1</b> on, among the first to fourth internal switches SW<b>1</b> to SW<b>4</b>. For example, in certain embodiments, in the second duration t<b>2</b> and the eighth duration t<b>8</b>, only the first LED array <b>221</b> are operated, and the second to fourth LED arrays <b>222</b> to <b>224</b> are not operated.

The voltage of the driving power V_RECin the third duration t<b>3</b> and the seventh duration t<b>7</b> may be sufficient to drive the first and second LED arrays <b>221</b> and <b>222</b> but may be insufficient to drive the first to third LED arrays <b>221</b> to <b>223</b> together. Therefore, the controller IC <b>212</b> may turn only the second internal switch SW<b>2</b> on and may turn the other switches SW<b>1</b>, SW<b>3</b>, and SW<b>4</b> off, in the third duration t<b>3</b> and the seventh duration t<b>7</b>. Consequently, a path of current I₂applied to the light source <b>220</b> in the third duration t<b>3</b> and the seventh duration t<b>7</b> may be defined as a path passing through the first and second LED arrays <b>221</b> and <b>222</b> and the second internal switch SW<b>2</b>. Therefore, in the third duration t<b>3</b> and the seventh duration t<b>7</b>, the first and second LED arrays <b>221</b> and <b>222</b> may be operated, and the third and fourth LED arrays <b>223</b> and <b>224</b> may not be operated.

Similarly, the voltage of the driving power V_RECin the fourth duration t<b>4</b> and the sixth duration t<b>6</b> may be sufficient to drive the first to third LED arrays <b>221</b> to <b>223</b> but may be insufficient to drive all of the first to fourth LED arrays <b>221</b> to <b>224</b> together. The controller IC <b>212</b> may set current I₃to pass through the first to third LED arrays <b>221</b> to <b>223</b> and the third internal switch SW<b>1</b> by turning only the third internal switch SW<b>1</b> on, in the fourth period t<b>4</b> and the sixth period t<b>6</b>. Therefore, in the fourth duration t<b>4</b> and the sixth duration t<b>6</b>, the first to third LED arrays <b>221</b> may be operated, and the fourth LED array <b>224</b> may not be operated.

The voltage magnitude of the driving power V_RECin the fifth duration t<b>5</b> may be sufficient to drive all of the first to fourth LED arrays <b>221</b> to <b>224</b>. Therefore, during the fifth period t<b>5</b>, the controller IC <b>212</b> may control all of the first to fourth LED arrays <b>221</b> to <b>224</b> to be operated by current I₄by turning the first to third internal switches SW<b>1</b> to SW<b>3</b> off and turning the fourth internal switch SW<b>4</b> on.

As illustrated in the waveform diagram of <figref idref="DRAWINGS">FIG. 4</figref>, currents flowing in the controller IC <b>212</b> may be different in the plurality of respective durations t<b>1</b>-t<b>9</b> included in a single cycle of the driving power V_REC. For example, in the fifth duration t<b>5</b>, the current I₄having the highest level may flow through the fourth internal switch SW<b>4</b> of the controller IC <b>212</b>. Therefore, a magnitude of the current I₄may be determined by a limiting current that may flow in the controller IC <b>212</b>, and consequently, a maximum output of the light source <b>220</b> may be determined by the limiting current that may flow in the controller IC <b>212</b>.

As illustrated in <figref idref="DRAWINGS">FIG. 2</figref>, the LED driving apparatus <b>210</b> may include the current controlling circuit <b>213</b> connected to an output terminal of the fourth LED array <b>224</b> and the fourth internal switch SW<b>4</b>. As shown in <figref idref="DRAWINGS">FIG. 2</figref>, each switch SW<b>1</b> through SW<b>4</b> may have one terminal connected to the current controlling circuit <b>213</b>, and one terminal connected to the light source <b>220</b>, for example, at an output terminal of a particular LED array. The current controlling circuit <b>213</b> may draw a portion of the current flowing in the LED arrays <b>221</b> to <b>224</b> in the fifth duration t<b>5</b> in which the fourth internal switch SW<b>4</b> is turned on, and thus, may decrease the current flowing in the fourth internal switch SW<b>4</b> during the fifth duration t<b>5</b>. As such, in the fifth duration t<b>5</b> in which the controller IC <b>212</b> receives the highest current stress, since a portion of the current I₄introduced to the controller IC <b>212</b> is dispersed into the current controlling circuit <b>213</b>, the limiting current of the LED driving apparatus <b>210</b> may be increased. Therefore, the LED driving apparatus <b>210</b> according to the exemplary embodiment of the present inventive concept may drive the light source <b>220</b> having a higher output.

Hereinafter, with reference to <figref idref="DRAWINGS">FIG. 3</figref>, a specific circuit configuration of the current controlling circuit <b>213</b> will be described.

Referring to <figref idref="DRAWINGS">FIG. 3</figref>, the current controlling circuit <b>213</b> according to certain exemplary embodiments may include switching elements Q<b>1</b> and Q<b>2</b> (also referred to as switches), resistors R<b>1</b> to R<b>3</b>, and a zener diode Z<b>1</b>. The zener diode Z<b>1</b> may be a clamping diode. The current controlling circuit <b>213</b> may be connected between a first terminal of a first internal switch of the plurality of internal switches (e.g., SW<b>4</b>) and a second terminal of the first internal switch of the plurality of internal switches. In addition, as described in more detail below, the current controlling circuit <b>213</b> may include a voltage divider connected between the first terminal of the first internal switch and a ground, and may further include at least one switch (e.g., Q<b>1</b>) connected to the second terminal of the first internal switch.

When the third internal switch SW<b>3</b> is turned off and the fourth internal switch SW<b>4</b> is turned on, current I_Lmay flow through a path including the first to fourth LED arrays <b>221</b> to <b>224</b> and the fourth internal switch SW<b>4</b>. Here, a magnitude of the current I_Lmay be identical to the magnitude of the current I₄illustrated in the waveform of <figref idref="DRAWINGS">FIG. 4</figref>. When the current I_Lflows, a gate voltage of the first switching element Q<b>1</b> may start to be increased by the resistor R<b>3</b> and the zener diode Z<b>1</b>, and the first switching element Q<b>1</b> may be turned on. When the first switching element Q<b>1</b> is turned on, the current I_Lmay be dispersed into current I_Sflowing in (e.g., through) the fourth internal switch SW<b>4</b> of the controller IC <b>212</b> and current I_Qflowing in (e.g., through) the first switching element Q<b>1</b>. Therefore, the current flowing in the controller IC <b>212</b> may be reduced, whereby current stress of the controller IC <b>212</b> may be lowered.

In this case, a ratio of the current I_Sflowing in the fourth internal switch SW<b>4</b> and the current I_Qflowing in the first switching element Q<b>1</b> may be determined by a ratio of the resistors R<b>1</b> and R<b>2</b>. Since both ends of the resistor R<b>2</b> may be respectively connected to base and emitter terminals of the second switching element Q<b>2</b> implemented as a bipolar transistor, a voltage at a terminal between the resistors R<b>1</b> and R<b>2</b> may be approximately 0.7V, and the current I_Sflowing in the fourth internal switch SW<b>4</b> may be determined as in the following mathematical equation 1. In the following mathematical equation 1, V_REFmay be a rated voltage of the controller IC <b>212</b>.

<maths id="MATH-US-00001" num="00001"><math overflow="scroll"><mtable><mtr><mtd><mrow><msub><mi>I</mi><mi>S</mi></msub><mo>=</mo><mfrac><mrow><msub><mi>V</mi><mi>REF</mi></msub><mo>-</mo><mn>0.7</mn></mrow><msub><mi>R</mi><mn>1</mn></msub></mfrac></mrow></mtd><mtd><mrow><mo>[</mo><mrow><mi>Mathematical</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mi>Equation</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mn>1</mn></mrow><mo>]</mo></mrow></mtd></mtr></mtable></math></maths><img file="US9686833B2_D0001.tif" />

Meanwhile, the current I_Qflowing in the first switching element Q<b>1</b> may be determined as in the following mathematical equation 2.

<maths id="MATH-US-00002" num="00002"><math overflow="scroll"><mtable><mtr><mtd><mrow><msub><mi>I</mi><mi>Q</mi></msub><mo>=</mo><mrow><mfrac><mn>0.7</mn><msub><mi>R</mi><mn>2</mn></msub></mfrac><mo>-</mo><mfrac><mrow><msub><mi>V</mi><mi>REF</mi></msub><mo>-</mo><mn>0.7</mn></mrow><msub><mi>R</mi><mn>1</mn></msub></mfrac></mrow></mrow></mtd><mtd><mrow><mo>[</mo><mrow><mi>Mathematical</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mi>Equation</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mn>2</mn></mrow><mo>]</mo></mrow></mtd></mtr></mtable></math></maths><img file="US9686833B2_D0002.tif" />

As such, the ratio of the current I_Sflowing in the fourth internal switch SW<b>4</b> and the current I_Qflowing in the first switching element Q<b>1</b> may be determined by the resistors R<b>1</b> and R<b>2</b>. Meanwhile, when it is defined by maximum current I that may flow in the controller IC <b>212</b>, a value of the resistor R<b>1</b> may be determined to satisfy the condition as in the following mathematical equation 3.

<maths id="MATH-US-00003" num="00003"><math overflow="scroll"><mtable><mtr><mtd><mrow><msub><mi>R</mi><mn>1</mn></msub><mo>≥</mo><mfrac><mrow><msub><mi>V</mi><mi>REF</mi></msub><mo>-</mo><mn>0.7</mn></mrow><msub><mi>I</mi><mi>MAX</mi></msub></mfrac></mrow></mtd><mtd><mrow><mo>[</mo><mrow><mi>Mathematical</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mi>Equation</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mn>3</mn></mrow><mo>]</mo></mrow></mtd></mtr></mtable></math></maths><img file="US9686833B2_D0003.tif" />

Thus, after the value of the resistor R<b>1</b> is first determined to satisfy the following mathematical equation 3, a value of the resistor R<b>2</b> may be determined to thereby configure the current controlling circuit <b>213</b>. A circuit configuration of the current controlling circuit <b>213</b> is not limited to that illustrated in <figref idref="DRAWINGS">FIG. 3</figref>, and may be implemented in other various forms. Since a main function of the current controlling circuit <b>213</b> is to draw and disperse a portion of the current flowing in the controller IC <b>212</b>, any circuit may be employed as the current controlling circuit <b>213</b>, as long as the circuit may be connected to one of the internal switches SW<b>1</b> to SW<b>4</b> and is configured to disperse an internal current flowing in the controller IC <b>212</b> when the corresponding internal switch SW<b>1</b> to SW<b>4</b> is turned on.

The exemplary embodiment illustrated in <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 3</figref> illustrates a case in which the current controlling circuit <b>213</b> is connected to only the fourth LED array <b>224</b> and the fourth internal switch SW<b>4</b>, but unlike this, the current controlling circuit <b>213</b> may also be connected to other LED arrays <b>221</b> to <b>223</b> and other internal switches SW<b>1</b> to SW<b>3</b>. The current controlling circuit <b>213</b> may be connected to the LED arrays <b>221</b> to <b>223</b> and the internal switches SW<b>1</b> to SW<b>3</b>, whereby a magnitude of the currents I₁-I₃supplied to the light source <b>220</b> in other durations not the fifth duration t<b>5</b> may be increased, and accordingly, an average magnitude of current I_LEDsupplied to the light source <b>220</b> within a single cycle of the driving power V_RECmay be increased to increase the output of the light source <b>220</b>.

<figref idref="DRAWINGS">FIG. 5</figref> is a circuit diagram illustrating an LED driving apparatus according to certain exemplary embodiments.

Referring to <figref idref="DRAWINGS">FIG. 5</figref>, an LED driving apparatus <b>310</b> according to an exemplary embodiment may include a rectifier circuit <b>311</b>, a controller IC <b>312</b>, a current controlling circuit <b>313</b>, a voltage detecting circuit <b>314</b>, and the like. Similar to the circuit diagram of <figref idref="DRAWINGS">FIG. 2</figref>, the rectifier circuit <b>311</b> may full-wave rectify AC power output by a power supply <b>330</b> to generate driving power. The controller IC <b>312</b> may determine the turning on/off of the internal switches SW<b>1</b> to SW<b>4</b> on the basis of a voltage magnitude of the driving power detected by the voltage detecting circuit <b>314</b>, and thus, may control operations of LED arrays <b>321</b> to <b>324</b> included in the light source <b>320</b>. The current controlling circuit <b>313</b> may be connected to one of the internal switches SW<b>1</b> to SW<b>4</b>, and may disperse the current I_LEDflowing in the LED arrays <b>321</b> to <b>324</b>, whereby current stress applied to the controller IC <b>312</b> may be reduced.

The light source <b>320</b> connected to the LED driving apparatus <b>310</b> illustrated in <figref idref="DRAWINGS">FIG. 5</figref> may include the LED arrays <b>321</b> to <b>324</b> having different numbers of LEDs. As illustrated in <figref idref="DRAWINGS">FIG. 5</figref>, the first LED array <b>321</b> may include the largest number of LEDs, and the fourth LED array <b>324</b> may include the smallest number of LEDs. The number of LEDs included in each of the LED arrays <b>321</b> to <b>324</b> may be determined as described above, and a power factor of the LED driving apparatus <b>310</b> may be increased. Meanwhile, the number of LEDs included in each of the LED arrays <b>321</b> to <b>324</b> may be variously modified. Also, in some embodiments, the numbers of some of LEDs in two or more different LED arrays may be the same, while the numbers of some LEDs in other LED arrays may be different. In some embodiments, at least one LED array includes a smaller number of LEDs than at least some of the remaining LED arrays of the plurality of LED arrays. The LED arrays described herein or light emitting device arrays described herein may generally be referred to as LED sets or light emitting device sets. As discussed in the embodiments above, each LED set or light emitting device set may have a plurality of LEDs/light emitting devices forming an array. In some embodiments, one of more LED or light emitting device sets may include only one LED/light emitting device.

<figref idref="DRAWINGS">FIG. 6</figref> is a waveform diagram provided for describing the LED driving apparatus illustrated in <figref idref="DRAWINGS">FIG. 5</figref>. The waveform diagram of <figref idref="DRAWINGS">FIG. 6</figref> is partially similar to the waveform diagram of FIG. <b>4</b>. For example, in the waveform diagram of <figref idref="DRAWINGS">FIG. 6</figref>, a single cycle of the driving power V_RECmay be divided into a total of nine durations t<b>1</b>′-t<b>9</b>′.

Relatively, since the first LED array <b>321</b> may include the largest number of LEDs, the first internal switch SW<b>1</b> may be turned on in the second and eighth durations t<b>2</b>′ and t<b>8</b>′, and a level of current I₁output by the LED driving apparatus <b>310</b> may be greater than that of the current I₁. Therefore, errors of the current I_LEDand the voltage V_RECof the driving power supplied to the LED arrays <b>321</b> to <b>324</b> in respective periods may be reduced, and consequently, the power factor may be improved.

In the embodiments of <figref idref="DRAWINGS">FIGS. 5 and 6</figref>, the operations of the current controlling circuit <b>313</b> may be similar to those described with reference to <figref idref="DRAWINGS">FIG. 2</figref> through <figref idref="DRAWINGS">FIG. 4</figref>. The current controlling circuit <b>313</b> may draw a portion of current I₄′ flowing in the LED arrays <b>321</b> to <b>324</b> in the fifth period t<b>5</b>′ in which the fourth internal switch SW<b>4</b> is turned on and all of the first to fourth LED arrays <b>321</b> to <b>324</b> are operated. Therefore, the current flowing in the controller IC <b>312</b> may be reduced to lower current stress of the controller IC <b>312</b>, and the LED arrays <b>321</b> to <b>324</b> having an increased output may be employed as the light source <b>320</b>, thereby implementing a high output lighting apparatus <b>300</b>.

<figref idref="DRAWINGS">FIG. 7</figref> through <figref idref="DRAWINGS">FIG. 12</figref> are views illustrating semiconductor light emitting devices applicable to a lighting apparatus according to certain exemplary embodiments of the present inventive concept. As described herein, light emitting devices may be in the form of light emitting diodes. As described in connection with some of the embodiments below, light emitting devices described herein may be semiconductor-type light emitting devices, and may emit light from an active layer of a semiconductor-type device.

Referring to <figref idref="DRAWINGS">FIG. 7</figref> first, a light emitting device <b>10</b> according to an exemplary embodiment of the present inventive concept may include a substrate <b>11</b>, a first conductivity-type semiconductor layer <b>12</b>, an active layer <b>13</b>, and a second conductivity-type semiconductor layer <b>14</b>. In addition, a first electrode <b>15</b> may be formed on the first conductivity-type semiconductor layer <b>12</b>, and a second electrode <b>16</b> may be formed on the second conductivity-type semiconductor layer <b>14</b>. An ohmic-contact layer may be further selectively provided between the second electrode <b>16</b> and the second conductivity-type semiconductor layer <b>14</b>.

First, according to various exemplary embodiments, the substrate <b>11</b> may be at least one selected from an insulating substrate, a conductive substrate, or a semiconductor substrate. The substrate <b>11</b> may be, for example, sapphire, SiC, Si, MgAl₂O₄, MgO, LiAlO₂, LiGaO₂, or GaN. A homogeneous substrate, a GaN substrate, may be selected as the substrate <b>11</b> for epitaxial growth of a GaN material, and a heterogeneous substrate may be, mainly, sapphire, silicon carbide (SiC) or the like. In the case of using the heterogeneous substrate, defects such as dislocations may be caused due to a difference in lattice constants between a substrate material and a film material. In addition, warpage may occur at the time of temperature variation due to a difference in coefficients of thermal expansion between the substrate material and the film material, and such a warpage phenomenon may cause cracks in the film. In order to reduce or remove such defects, a buffer layer <b>11</b><i>a </i>may be disposed between the substrate <b>11</b> and the first conductivity-type semiconductor layer <b>12</b> provided as a GaN based layer.

In the case of growing the first conductivity-type semiconductor layer <b>12</b> containing GaN on the heterogeneous substrate, dislocation density may be increased due to a mismatch in lattice constants between the substrate material and the film material, and cracks and warpage may occur due to the difference in coefficients of thermal expansion. In order to prevent the dislocation and cracks as described above, the buffer layer <b>11</b><i>a </i>may be disposed between the substrate <b>11</b> and the first conductivity-type semiconductor layer <b>12</b>. The buffer layer <b>11</b><i>a </i>may adjust a degree of warpage of the substrate when an active layer is grown, and may reduce wavelength dispersion of a wafer.

The buffer layer <b>11</b><i>a </i>may be made of Al_xIn_yGa_1−x−yN (0≦x≦1, 0≦y≦1), in particular, GaN, AlN, AlGaN, InGaN, or InGaN/AlN, and a material such as ZrB₂, HfB₂, ZrN, HfN, TiN, or the like, may also be used. Also, the buffer layer may be formed by combining a plurality of layers or by gradually changing a composition.

A silicon (Si) substrate has a coefficient of thermal expansion significantly different from that of GaN. Thus, in a case of growing a GaN-based film on the silicon substrate, when a GaN film is grown at a high temperature and is subsequently cooled to room temperature, tensile stress is applied to the GaN film due to the difference in the coefficients of thermal expansion between the silicon substrate and the GaN film, causing cracks. In this case, in order to prevent the occurrence of cracks, a method of growing the GaN film such that compressive stress is applied to the GaN film while the GaN film is being grown is used to compensate for tensile stress. A significant difference in lattice constants between silicon (Si) and GaN involves a high possibility of the occurrence of defects. In the case of using a silicon substrate, the buffer layer <b>11</b><i>a </i>having a composite structure may be used in order to control stress for restraining warpage as well as controlling defects.

First, an AlN layer may be formed on the substrate <b>11</b> in order to form the buffer layer <b>11</b><i>a</i>. In this case, a material not including gallium (Ga) may be used in order to prevent a reaction between silicon (Si) and gallium (Ga). Besides AlN, a material such as SiC, or the like, may also be used. The AlN layer may be grown at a temperature ranging from about 400° C. to about 1300° C. by using an aluminum (Al) source and a nitrogen (N) source. An AlGaN interlayer may be inserted between a plurality of AlN layers in order to control stress in the middle of GaN.

The first conductivity-type semiconductor layer <b>12</b> and the second conductivity-type semiconductor layer <b>14</b> may be an n-type impurity doped semiconductor layer and a p-type impurity doped semiconductor layer, respectively, but are not limited thereto. The first conductivity-type semiconductor layer <b>12</b> and the second conductivity-type semiconductor layer <b>14</b> may be a p-type semiconductor layer and an n-type semiconductor layer, respectively. By way of example, the first conductivity-type semiconductor layer <b>12</b> and the second conductivity-type semiconductor layer <b>14</b> may be formed of a group III nitride semiconductor, such as a material having a composition of Al_xIn_yGa_1−x−yN (0≦x≦1, 0≦y≦1, 0≦x+y≦1). The materials of the first conductivity-type semiconductor layer <b>12</b> and the second conductivity-type semiconductor layer <b>14</b> are not limited thereto, and may be, for example, an AlGaInP based semiconductor or an AlGaAs based semiconductor.

The first and second conductivity-type semiconductor layers <b>12</b> and <b>14</b> may have a single layer structure, but may alternatively have a multilayer structure in which respective layers have different compositions, thicknesses, or the like, if desired or necessary. For example, each of the first and second conductivity-type semiconductor layers <b>12</b> and <b>14</b> may include a carrier injection layer capable of improving injection efficiency of electrons and holes, and further, may have a superlattice structure formed in various manners.

The first conductivity-type semiconductor layer <b>12</b> may further include a current spreading layer in a portion thereof adjacent to the active layer <b>13</b>. The current spreading layer may have a structure, for example, in which a plurality of Al_xIn_yGa_1−x−yN layers having different compositions or different impurity contents are repeatedly stacked, or may be partially formed of an insulating material layer.

The second conductivity-type semiconductor layer <b>14</b> may further include an electron blocking layer in a portion thereof adjacent to the active layer <b>13</b>. The electron blocking layer may have a structure, for example, in which a plurality of Al_xIn_yGa_1−x−yN layers having different compositions are stacked or may have at least one layer configured of Al_yGa_(1−y)N. The second conductivity-type semiconductor layer <b>14</b> may have a band gap greater than that of the active layer <b>13</b> to prevent electrons from passing over the second conductivity-type semiconductor layer <b>14</b>.

In an exemplary embodiment, the first and second conductivity-type semiconductor layers <b>12</b> and <b>14</b> and the active layer <b>13</b> may be formed using an MOCVD device. In order to manufacture the first and second conductivity-type semiconductor layers <b>12</b> and <b>14</b> and the active layer <b>13</b>, according to certain embodiments, an organic metal compound gas (for example, trimethylgallium (TMG), trimethyl aluminum (TMA), or the like) and a nitrogen-containing gas (ammonia (NH₃) or the like) are supplied as a reaction gas to a reaction container in which the growth substrate <b>11</b> is installed, and a temperature of the substrate is maintained at a high temperature of 900° C. to 1100° C., and thus gallium nitride compound semiconductors may be grown on the substrate while supplying an impurity gas thereto if necessary, to thereby allow the gallium nitride compound semiconductors to be stacked as an undoped layer, an n-type layer, and a p-type layer, on the substrate. An n-type impurity may be Si, widely known in the art, and a p-type impurity may be Zn, Cd, Be, Mg, Ca, Ba, or the like. As the p-type impurity, Mg and Zn may be mainly used.

In addition, the active layer <b>13</b> interposed between the first and second conductivity-type semiconductor layers <b>12</b> and <b>14</b> may have a multiple quantum well (MQW) structure in which quantum well layers and quantum barrier layers are alternately stacked. For example, in the case in which the active layer <b>13</b> includes a nitride semiconductor, the active layer <b>13</b> may have a structure of GaN and InGaN. Depending on exemplary embodiments, the active layer <b>13</b> may have a single quantum well (SQW) structure. The first or second electrode <b>15</b> or <b>16</b> may contain a material such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, or the like. The light emitting device <b>10</b> illustrated in <figref idref="DRAWINGS">FIG. 7</figref> may have an Epi-Up structure, and accordingly, may be electrically connected to a circuit pattern included in a circuit board by a wire or the like within a light emitting device package.

Then, referring to <figref idref="DRAWINGS">FIG. 8</figref>, a light emitting device <b>20</b> according to another exemplary embodiment of the present inventive concept may include a support substrate <b>21</b>, first and second conductivity-type semiconductor layers <b>22</b> and <b>24</b>, an active layer <b>23</b>, first and second electrodes <b>25</b> and <b>26</b>, and the like. The light emitting device <b>20</b> according to the exemplary embodiment illustrated in <figref idref="DRAWINGS">FIG. 8</figref> may be attached to a circuit board of a light emitting device package by flip-chip bonding. Since light generated in the active layer <b>23</b> needs to be emitted upwardly, the support substrate <b>21</b> may be formed of a material having light-transmissive properties.

In addition, in order to reflect light generated in the active layer <b>23</b> and moving in a downward direction, the second electrode <b>26</b> may be formed of a material having excellent electrical conductivity and reflectance properties. In an example, the second electrode <b>26</b> may be formed of at least one among Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, and Au.

Then, referring to <figref idref="DRAWINGS">FIG. 9</figref>, a light emitting device <b>30</b> according to another exemplary embodiment is illustrated. The light emitting device <b>30</b> according to the embodiment illustrated in <figref idref="DRAWINGS">FIG. 9</figref> may include a first conductivity-type semiconductor layer <b>32</b>, an active layer <b>33</b>, a second conductivity-type semiconductor layer <b>34</b>, a first electrode <b>35</b> attached to the first conductivity-type semiconductor layer <b>32</b>, and a second electrode <b>36</b> attached to the second conductivity-type semiconductor layer <b>34</b>, and the like. A conductive substrate <b>31</b> may be disposed on a lower surface of the second electrode <b>36</b>, and may be directly mounted on a circuit board for configuring a light emitting device package. Within the light emitting device package, the conductive substrate <b>31</b> may be directly mounted on the circuit board, and the first electrode <b>35</b> may be electrically connected to the circuit pattern of the circuit board by a wire, or the like.

In a similar manner to the case of the semiconductor light emitting devices <b>10</b> and <b>20</b>, the first conductivity-type semiconductor layer <b>32</b> and the second conductivity-type semiconductor layer <b>34</b> may include an n-type nitride semiconductor and a p-type nitride semiconductor, respectively. The active layer <b>33</b> interposed between the first and second conductivity-type semiconductor layers <b>32</b> and <b>34</b> may have a multiple quantum well (MQW) structure in which nitride semiconductor layers having different compositions are alternately stacked, and may selectively have a single quantum well (SQW) structure.

The first electrode <b>35</b> may be disposed on an upper surface of the first conductivity-type semiconductor layer <b>32</b>, and the second electrode <b>36</b> may be disposed on a lower surface of the second conductivity-type semiconductor layer <b>34</b>. Light generated due to the recombination of electrons and holes in the active layer <b>33</b> of the light emitting device <b>30</b> shown in <figref idref="DRAWINGS">FIG. 9</figref> may be emitted to an upper surface of the first conductivity-type semiconductor layer <b>32</b> on which the first electrode <b>35</b> is disposed. Thus, in order to reflect light generated in the active layer <b>33</b> in a direction toward the upper surface of the first conductivity-type semiconductor layer <b>32</b>, the second electrode <b>36</b> may be formed of a material having a high degree of reflectance. The second electrode <b>36</b> may contain at least one of Ag, Al, Ni, Cr, Cu, Au, Pd, Pt, Sn, Ti, W, Rh, Ir, Ru, Mg, and Zn, or an alloy containing these materials.

Then, referring to <figref idref="DRAWINGS">FIG. 10</figref>, a light emitting device <b>40</b> according to the exemplary embodiment may include a first conductivity-type semiconductor layer <b>42</b>, a second conductivity-type semiconductor layer <b>44</b>, an active layer <b>43</b> interposed therebetween, and first and second electrodes <b>45</b> and <b>46</b> connected to the first and second conductivity-type semiconductor layers <b>42</b> and <b>44</b>, respectively. In the exemplary embodiment, the first and second electrodes <b>45</b> and <b>46</b> may be disposed on opposite surfaces of the first and second conductivity-type semiconductor layers <b>42</b> and <b>44</b>, and the active layer <b>43</b> may be interposed between the first and second electrodes <b>45</b> and <b>46</b>. A support substrate <b>41</b> may be attached to the second electrode <b>46</b> by a bonding layer <b>41</b><i>a </i>and may support the light emitting device <b>40</b>.

The light emitting device <b>40</b> according to the exemplary embodiment of <figref idref="DRAWINGS">FIG. 10</figref> may further include a connecting electrode <b>47</b> as an electrode element in association with the second electrode <b>46</b>. The connecting electrode <b>47</b> may be connected to the second electrode <b>46</b> through a through-hole H formed by at least partially removing the first and second conductive-type semiconductor layers <b>42</b> and <b>44</b> and the active layer <b>43</b>. At least a portion of the second electrode <b>46</b> may be exposed through the through-hole H, and, in the exposed portion, the second electrode <b>46</b> and the connecting electrode <b>47</b> may be connected to each other. The connecting electrode <b>47</b> may be formed along a sidewall of the through-hole H, and an insulating layer <b>47</b><i>a </i>may be provided between the connecting electrode <b>47</b> and the sidewall of the through hole H in order to prevent electrical connections between the connecting electrode <b>47</b> and the active layer <b>43</b> and the first conductivity-type semiconductor layer <b>42</b>.

Such an electrode structure may be further efficiently applied to a form in which the first and second conductivity-type semiconductor layers <b>42</b> and <b>44</b> are n-type and p-type nitride semiconductor layers, respectively. Since the p-type nitride semiconductor layer has a degree of contact resistance greater than that of the n-type nitride semiconductor layer, it may be difficult to obtain ohmic-contact. However, in the exemplary embodiment illustrated in <figref idref="DRAWINGS">FIG. 10</figref>, since the second electrode <b>46</b> is disposed over the entire surface of the support substrate <b>41</b>, a contact area between the second conductivity-type semiconductor layer <b>44</b> and the second electrode <b>46</b> may be sufficiently secured, whereby ohmic-contact between the second electrode <b>46</b> and the p-type nitride semiconductor layer may be obtained.

The light emitting device <b>40</b> according to the exemplary embodiment illustrated in <figref idref="DRAWINGS">FIG. 10</figref> may have a flip-chip structure in which light is emitted in a direction toward the support substrate <b>41</b>. For example, the first electrode <b>45</b> and the connecting electrode <b>47</b> may be electrically connected to circuit patterns <b>49</b><i>a </i>of a circuit board <b>49</b> by solder bumps <b>48</b>. Thus, the first electrode <b>45</b> may contain an electrode material having a high degree of reflectance as well as ohmic-contact characteristics. The second electrode <b>46</b> and the support substrate <b>41</b> may have high light-transmissive properties. For example, the first electrode <b>45</b> may contain a material such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, or the like. The second electrode <b>46</b> may be formed of a light-transmissive metal such as Ni/Au, or may be formed of a transparent conductive oxide or nitride such as ITO. The support substrate <b>41</b> may be a glass substrate or a substrate formed of a light-transmissive polymer resin.

The connecting electrode <b>47</b> may be electrically insulated from the first conductivity-type semiconductor layer <b>42</b> and the active layer <b>43</b> by the insulating layer <b>47</b><i>a</i>. As illustrated in <figref idref="DRAWINGS">FIG. 8</figref>, the insulating layer <b>47</b><i>a </i>may be formed along the sidewall of the through-hole H. In addition, the insulating layer <b>47</b><i>a </i>may be formed on side surfaces of the first and second conductivity-type semiconductor layers <b>42</b> and <b>44</b> and the active layer <b>43</b>, and may be provided as a passivation layer for the light emitting device <b>10</b>. The insulating layer <b>47</b><i>a </i>may contain, for example, a silicon oxide or a silicon nitride.

Referring to <figref idref="DRAWINGS">FIG. 11</figref>, a light emitting device <b>50</b> according to another exemplary embodiment is disclosed. The light emitting device <b>50</b> may include a first conductivity-type semiconductor layer <b>52</b>, an active layer <b>53</b>, and a second conductivity-type semiconductor layer <b>54</b> sequentially stacked on one surface of a substrate <b>51</b>, and first and second electrodes <b>55</b> and <b>56</b>. In addition, the light emitting device <b>50</b> may include an insulating portion <b>57</b>. The first and second electrodes <b>55</b> and <b>56</b> may include contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a </i>and connecting electrodes <b>55</b><i>b </i>and <b>56</b><i>b</i>, and partial regions of the contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a </i>exposed by the insulating portion <b>57</b> may be connected to the connecting electrodes <b>55</b><i>b </i>and <b>56</b><i>b. </i>

The first contact electrode <b>55</b><i>a </i>may be provided as a conductive via penetrating through the second conductivity-type semiconductor layer <b>54</b> and the active layer <b>53</b> to be connected to the first conductivity-type semiconductor layer <b>52</b>. The second contact electrode <b>56</b><i>a </i>may be connected to the second conductivity-type semiconductor layer <b>54</b>. A plurality of conductive vias may be provided in a single region of the light emitting device.

A conductive ohmic material may be deposited on the first and second conductivity-type semiconductor layers <b>52</b> and <b>54</b> to form first and second contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a</i>. The first and second contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a </i>may contain at least one of Ag, Al, Ni, Cr, Cu, Au, Pd, Pt, Sn, Ti, W, Rh, Ir, Ru, Mg, and Zn, or an alloy containing these materials. In addition, the second contact electrode <b>56</b><i>a </i>may serve to reflect light generated in the active layer <b>53</b> and emitted downwardly of the light emitting device <b>50</b>.

The insulating portion <b>57</b> may have open regions through which at least portions of the first and second contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a </i>are exposed, and the first and second connecting electrodes <b>55</b><i>b </i>and <b>56</b><i>b </i>may be connected to the first and second contact electrodes <b>55</b><i>a </i>and <b>56</b><i>a</i>, respectively. The insulating portion <b>57</b> may be deposited at a thickness, for example, of 0.01 μm to 3 μm at a temperature of 500° C. or lower through a SiO₂and/or SiN CVD process. The first and second electrodes <b>55</b> and <b>56</b> may be mounted on the light emitting device package in a flip-chip scheme.

The first and second electrodes <b>55</b> and <b>56</b> may be electrically isolated from each other by the insulating portion <b>57</b>. Although the insulating portion <b>57</b> may be formed of any material as long as the material has electrical insulation properties, the insulating portion <b>57</b> may preferably be formed of a material having a low light absorption rate in order to prevent a deterioration in light extraction efficiency. For example, a silicon oxide or a silicon nitride such as SiO₂, SiO_xN_y, Si_xN_y, or the like may be used. If necessary, a light reflecting structure may be formed by dispersing light reflective fillers in a light-transmissive material.

The substrate <b>51</b> may have first and second surfaces opposed to each other. An uneven structure may be formed on at least one of the first and second surfaces. The uneven structure formed on one surface of the substrate <b>51</b> may be formed by etching a portion of the substrate <b>51</b>, and may be formed of the same material as that of the substrate <b>51</b>, or may be configured of a heteromaterial different from that of the substrate <b>51</b>. For example, an uneven structure may be formed on an interface between the substrate <b>51</b> and the first conductivity-type semiconductor layer <b>52</b>, and thus a path of light emitted from the active layer <b>53</b> may be variously formed. Thus, a ratio at which light is absorbed in the interior of a semiconductor layer may be reduced, and a light scattering ratio may be increased to thereby enhance light extraction efficiency. In addition, a buffer layer may be provided between the first substrate <b>51</b> and the first conductivity-type semiconductor layer <b>52</b>.

Referring to <figref idref="DRAWINGS">FIG. 12</figref>, a light emitting device <b>60</b> according to another exemplary embodiment concept includes a light emitting device <b>60</b> having a light emitting nanostructure. The light emitting device <b>60</b> may include abase layer <b>62</b>′ containing a first conductivity-type semiconductor material, a mask layer <b>67</b> provided on the base layer <b>62</b>′ and providing a plurality of openings, and nanocores <b>62</b> formed in the openings of the mask layer <b>67</b>. On the nanocores <b>62</b>, active layers <b>63</b> and second conductivity-type semiconductor layers <b>64</b> may be provided. The nanocores <b>62</b>, the active layers <b>63</b>, and the second conductivity-type semiconductor layers <b>64</b> may provide the light emitting nanostructure.

A second contact electrode <b>66</b><i>a </i>may be prepared on the second conductivity-type semiconductor layers <b>64</b>, and a second connecting electrode <b>66</b><i>b </i>may be provided on one surface of the second contact electrode <b>66</b><i>a</i>. The second contact electrode <b>66</b><i>a </i>and the second connecting electrode <b>66</b><i>b </i>may be provided as a second electrode <b>66</b>. A support substrate <b>61</b> may be attached to one surface of the second electrode <b>66</b>, and may be a conductive substrate or an insulating substrate. In the case in which the support substrate <b>61</b> has conductivity, the support substrate <b>61</b> may be directly mounted on a circuit board of a light emitting device package. A first electrode <b>65</b> may be provided on the base layer <b>62</b>′ containing a first conductivity-type semiconductor material. The first electrode <b>65</b> may be connected to a circuit pattern included in the circuit board of the light emitting device package by a wire, or the like.

<figref idref="DRAWINGS">FIG. 13A</figref> and <figref idref="DRAWINGS">FIG. 13B</figref> are views schematically illustrating white light source modules applicable to a lighting apparatus according to an exemplary embodiment. <figref idref="DRAWINGS">FIG. 14</figref> is a CIE 1931 color space chromaticity diagram provided for describing operations of the white light source modules illustrated in <figref idref="DRAWINGS">FIG. 13A</figref> and <figref idref="DRAWINGS">FIG. 13B</figref>.

Each of the white light source modules illustrated in <figref idref="DRAWINGS">FIG. 13A</figref> and <figref idref="DRAWINGS">FIG. 13B</figref> may include a plurality of light emitting device packages. The plurality of light emitting device packages mounted in a single white light source module may be configured of the same kinds of packages generating light having the same wavelength, but in some embodiments, may also be configured of different types of packages generating light having different wavelengths.

Referring to <figref idref="DRAWINGS">FIG. 13A</figref>, the white light source module may be configured by combining a white light emitting device package ‘40’ having a color temperature of 4000K, a white light emitting device package ‘30’ having a color temperature of 3000K, and a red light emitting device package R. The white light source module may allow a color temperature thereof to be adjusted within a range of 3000K to 4000K, and may provide white light having a color rendering index Ra of 85 to 100.

In another embodiment, the white light source module may be configured of only white light emitting device packages, and, in this case, some of the packages may generate white light having different color temperatures. For example, as illustrated in <figref idref="DRAWINGS">FIG. 13B</figref>, a white light emitting device package ‘27’ having a color temperature of 2700K and a white light emitting device package ‘50’ having a color temperature of 5000K may be combined to provide white light in which a color temperature thereof may be adjusted within a range of 2700K to 5000K, and a color rendering index Ra thereof is 85 to 100. Here, the number of light emitting device packages having respective color temperatures may mainly be varied depending on a basic, predetermined value of a color temperature. In the case of a lighting apparatus in which the basic, predetermined value of the color temperature is in the vicinity of 4000K, for example, the number of light emitting device packages corresponding to the color temperature of 4000K may be greater than that of light emitting device packages having a color temperature of 3000K or red light emitting device packages.

In this manner, different types of light emitting device packages may be configured to include at least one of a violet, blue, green, red or infrared light emitting device, and a light emitting device generating white light formed by combining yellow, green, red or orange phosphors with a blue light emitting device, whereby a color temperature and a color rendering index of white light may be adjusted. The white light source module may be employed as a light source in lighting apparatuses having various forms.

A single light emitting device package may determine light of desired color depending on a wavelength of an LED chip, a light emitting device, and kinds and a mixing ratio of phosphors, and in the case of white light, may adjust a color temperature and a color rendering index thereof.

For example, when the LED chip emits blue light, a light emitting device package including at least one of a yellow phosphor, a green phosphor, and a red phosphor may emit white light having various color temperatures by adjusting a mixing ratio of the phosphors. Unlike this, a light emitting device package applying a green or red phosphor to a blue LED chip may emit green or red light. In this manner, a color temperature and a color rendering index (CRI) of white light may be adjusted by combining a light emitting device package emitting white light with a package emitting green or red light. In addition, the light emitting device package may be configured to include at least one of light emitting devices emitting violet, blue, green, red, or infrared light.

In this case, a lighting apparatus may adjust a color rendering index (CRI) from a natrium (Na) to a solar light level, and may generate various types of white light with color temperatures ranging from 2000K to 20,000K. Also, if necessary, the lighting apparatus may generate violet, blue, green, red, or orange visible light, or infrared light, to adjust the color of light according to a surrounding atmosphere and a user's mood. Also, the lighting apparatus may generate a specific wavelength of light for accelerating the growth of plants.

White light formed by combining yellow, green, and red phosphors with a blue light emitting device and/or combining green and red light emitting devices may have two or more peak wavelengths, and coordinates (x, y) thereof in the CIE 1931 color space chromaticity diagram of <figref idref="DRAWINGS">FIG. 14</figref> may be positioned on a line segment connecting (0.4476, 0.4074), (0.3484, 0.3516), (0.3101, 0.3162), (0.3128, 0.3292), and (0.3333, 0.3333). Alternatively, coordinates (x, y) thereof in the CIE 1931 color space chromaticity diagram may be positioned in a region surrounded by the line segment and blackbody radiation spectrum. The color temperature of white light may range from 1500K to 20000K. In <figref idref="DRAWINGS">FIG. 14</figref>, white light in the vicinity of point E (0.3333, 0.3333), disposed below the blackbody radiation spectrum, may be in a state in which a level of yellow light is relatively low, and may be used as a light source in a region exhibiting a brighter or fresher feeling. Therefore, lighting products using white light in the vicinity of point E (0.3333, 0.3333), disposed below the blackbody radiation spectrum, may be highly effective as lighting apparatuses for retail spaces selling groceries, clothing, and the like.

<figref idref="DRAWINGS">FIG. 15</figref> is a view illustrating a wavelength conversion material applicable to a light source of a lighting apparatus according to an exemplary embodiment.

Various materials such as phosphors and/or quantum dots may be used as the wavelength conversion material, a material for converting a wavelength of light emitted from the light emitting device.

In an exemplary embodiment, the phosphors applied to the wavelength conversion material may have the following empirical formulas and colors:

Oxides: Yellow and green Y₃Al₅O₁₂:Ce, Tb₃Al₅O₁₂:Ce, Lu₃Al₅O₁₂:Ce

Silicates: Yellow and green (Ba,Sr)₂SiO₄:Eu, yellow and orange (Ba, Sr)₃SiO₅:Ce

Nitrides: Green β-SiAlON:Eu, yellow La₃Si₆N₁1:Ce, orange α-SiAlON:Eu, red CaAlSiN₃:Eu, Sr₂Si₅N₈:Eu, SrSiAl₄N₇:Eu, SrLiAl₃N₄:Eu, <br />Ln_4−x(Eu_zM_1−z)_xSi_12−yAl_yO_3+x+yN_18−x−y(0.5<i>≦x≦</i>3,0<i>&lt;z&lt;</i>0.3,0<i>&lt;y≦</i>4)  Equation (1)

In Equation (1), Ln may be at least one type of element selected from the group consisting of Group IIIa elements and rare earth elements, and M may be at least one type of element selected from the group consisting of calcium (Ca), barium (Ba), strontium (Sr), and magnesium (Mg).

Fluorides: KSF-based red K₂SiF₆:Mn₄⁺, K₂TiF₆:Mn₄⁺, NaYF₄:Mn₄⁺, NaGdF₄:Mn₄⁺ (for example, a composition ratio of Mn may be 0&lt;z&lt;=0.17).

Phosphor compositions should basically conform with stoichiometry, and respective elements may be substituted with other elements of respective groups of the periodic table. For example, strontium (Sr) may be substituted with barium (Ba), calcium (Ca), magnesium (Mg), and the like within the alkaline earth group (II), and yttrium (Y) may be substituted with lanthanum (La) based elements such as terbium (Tb), lutetium (Lu), scandium (Sc), gadolinium (Gd), and the like. Also, europium (Eu), an activator, may be substituted with cerium (Ce), terbium (Tb), praseodymium (Pr), erbium (Er), ytterbium (Yb), and the like, according to a desired energy level, and an activator may be applied alone or with a co-activator for modifying characteristics of phosphors.

In particular, in order to enhance reliability at high temperatures and high humidity, a fluoride-based red phosphor may be coated with a fluoride not containing manganese (Mn) or with organic materials thereon. The organic materials may be coated on the fluoride-based red phosphor coated with a fluoride not containing manganese (Mn). Unlike other phosphors, the fluoride-based red phosphor may realize a narrow full width at half maximum (FWHM) equal to or less than 40 nm, and thus, it may be utilized in high resolution TVs such as UHD TVs.

Table 1 below illustrates types of phosphors in application fields of light emitting device packages using a blue LED chip having a wavelength of 440 nm to 460 nm, or a UV LED chip having a wavelength of 380 nm to 440 nm.

<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="77pt" align="left" /><colspec colname="2" colwidth="126pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 1</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>USE</entry><entry>Phosphor</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>LED TV BLU</entry><entry>β-SiAlON:Eu2+ </entry></row><row><entry /><entry /><entry>(Ca, Sr)AlSiN₃:Eu2+</entry></row><row><entry /><entry /><entry>La₃Si₆N₁₁:Ce3+</entry></row><row><entry /><entry /><entry>K₂SiF₆:Mn4+</entry></row><row><entry /><entry /><entry>SrLiAl3N4:Eu</entry></row><row><entry /><entry /><entry>Ln_4-x(Eu_zM_1-z)_xSi_12-yAl_yO_3+x+yN_18-x-y</entry></row><row><entry /><entry /><entry>(0.5 ≦ x ≦ 3, 0 &lt; z &lt; 0.3, 0 &lt; y ≦ 4)</entry></row><row><entry /><entry /><entry>K2TiF6:Mn4+</entry></row><row><entry /><entry /><entry>NaYF4:Mn4+</entry></row><row><entry /><entry /><entry>NaGdF4:Mn4+</entry></row><row><entry /><entry>Lighting</entry><entry>Lu₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry>device</entry><entry>Ca-α-SiAlON:Eu2+</entry></row><row><entry /><entry /><entry>La₃Si₆N₁₁:Ce3+</entry></row><row><entry /><entry /><entry>(Ca, Sr)AlSiN₃:Eu2+</entry></row><row><entry /><entry /><entry>Y₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry /><entry>K₂SiF₆:Mn4+</entry></row><row><entry /><entry /><entry>SrLiAl3N4:Eu</entry></row><row><entry /><entry /><entry>Ln_4-x(Eu_zM_1-z)_xSi_12-yAl_yO_3+x+yN_18-x-y</entry></row><row><entry /><entry /><entry>(0.5 ≦ x ≦ 3, 0 &lt; z &lt; 0.3, 0 &lt; y ≦ 4)</entry></row><row><entry /><entry /><entry>K2TiF6:Mn4+</entry></row><row><entry /><entry /><entry>NaYF4:Mn4+</entry></row><row><entry /><entry /><entry>NaGdF4:Mn4+</entry></row><row><entry /><entry>Side View</entry><entry>Lu₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry>(Mobile, Note PC)</entry><entry>Ca-α-SiAlON:Eu2+</entry></row><row><entry /><entry /><entry>La₃Si₆N₁₁:Ce3+</entry></row><row><entry /><entry /><entry>(Ca, Sr)AlSiN₃:Eu2+</entry></row><row><entry /><entry /><entry>Y₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry /><entry>(Sr, Ba, Ca, Mg)2SiO4:Eu2+</entry></row><row><entry /><entry /><entry>K₂SiF₆:Mn4+</entry></row><row><entry /><entry /><entry>SrLiAl3N4:Eu</entry></row><row><entry /><entry /><entry>Ln_4-x(Eu_zM_1-z)_xSi_12-yAl_yO_3+x+yN_18-x-y</entry></row><row><entry /><entry /><entry>(0.5 ≦ x ≦ 3, 0 &lt; z &lt; 0.3, 0 &lt; y ≦ 4)</entry></row><row><entry /><entry /><entry>K2TiF6:Mn4+</entry></row><row><entry /><entry /><entry>NaYF4:Mn4+</entry></row><row><entry /><entry /><entry>NaGdF4:Mn4+</entry></row><row><entry /><entry>Electronic</entry><entry>Lu₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry>device</entry><entry>Ca-α-SiAlON:Eu2+</entry></row><row><entry /><entry>(Head Lamp, etc.)</entry><entry>La₃Si₆N₁₁:Ce3+</entry></row><row><entry /><entry /><entry>(Ca, Sr)AlSiN₃:Eu2+</entry></row><row><entry /><entry /><entry>Y₃Al₅O₁₂:Ce3+</entry></row><row><entry /><entry /><entry>K₂SiF₆:Mn4+</entry></row><row><entry /><entry /><entry>SrLiAl3N4:Eu</entry></row><row><entry /><entry /><entry>Ln_4-x(Eu_zM_1-z)_xSi_12-yAl_yO_3+x+yN_18-x-y</entry></row><row><entry /><entry /><entry>(0.5 ≦ x ≦ 3, 0 &lt; z &lt; 0.3, 0 &lt; y ≦ 4)</entry></row><row><entry /><entry /><entry>K2TiF6:Mn4+</entry></row><row><entry /><entry /><entry>NaYF4:Mn4+</entry></row><row><entry /><entry /><entry>NaGdF4:Mn4+</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

The wavelength conversion material may include quantum dots (QD) provided to be used in place of phosphors or to be mixed with phosphors.

<figref idref="DRAWINGS">FIG. 15</figref> is a view illustrating a cross-sectional structure of a quantum dot. The quantum dot may have a core-shell structure including Group II-VI or Group III-V compound semiconductors. For example, the quantum dot may have a core such as CdSe or InP, or a shell such as ZnS or ZnSe. Also, the quantum dot may include a ligand to stabilize the core and shell. For example, the core may have a diameter ranging from 1 nm to 30 nm, and preferably, 3 nm to 10 nm in an exemplary embodiment. The shell may have a thickness ranging from 0.1 nm to 20 nm, and preferably, 0.5 nm to 2 nm in an exemplary embodiment.

The quantum dots may realize various colors according to sizes, and, in particular, when the quantum dot is used as a phosphor substitute, it may be used as a red or green phosphor. The use of a quantum dot may realize a narrow FWHM (e.g., about 35 nm).

The wavelength conversion material may be provided in the form of being contained in an encapsulator, or alternatively, the wavelength conversion material may be manufactured as a film in advance and attached to a surface of an optical device such as an LED chip or a light guide plate. In the case of using the wavelength conversion material manufactured as a film in advance, a wavelength conversion material having a uniform thickness may be easily implemented.

<figref idref="DRAWINGS">FIG. 16</figref> through <figref idref="DRAWINGS">FIG. 24</figref> are views illustrating backlight units including the LED driving apparatus according to certain exemplary embodiments.

Referring to <figref idref="DRAWINGS">FIG. 16</figref>, a backlight unit <b>1000</b> may include a light guide plate <b>1040</b> and light source modules <b>1010</b> provided on both sides of the light guide plate <b>1040</b>. Also, the backlight unit <b>1000</b> may further include a reflective plate <b>1020</b> disposed below the light guide plate <b>1040</b>. The backlight unit <b>1000</b> according to the exemplary embodiment of <figref idref="DRAWINGS">FIG. 16</figref> may be an edge type backlight unit.

According to an exemplary embodiment, the light source module <b>1010</b> may be provided only on one side of the light guide plate <b>1040</b>, or may further be provided on the other side thereof. The light source module <b>1010</b> may include a printed circuit board (PCB) <b>1001</b> and a plurality of light sources <b>1005</b> mounted on an upper surface of the PCB <b>1001</b>. The plurality of light sources <b>1005</b> may be driven by the LED driving apparatus <b>110</b>, <b>210</b>, or <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

<figref idref="DRAWINGS">FIG. 17</figref> is a view illustrating an embodiment of a direct type backlight unit.

Referring to <figref idref="DRAWINGS">FIG. 17</figref>, a backlight unit <b>1100</b> may include a light diffuser plate <b>1140</b> and a light source module <b>1110</b> arranged below the light diffuser plate <b>1140</b>. Also, the backlight unit <b>1100</b> may further include a bottom case <b>1160</b> disposed below the light diffuser plate <b>1140</b> and accommodating the light source module <b>1110</b>. The backlight unit <b>1100</b> according to the exemplary embodiment may be a direct type backlight unit.

The light source module <b>1110</b> may include a printed circuit board (PCB) <b>1101</b> and a plurality of light sources <b>1105</b> mounted on an upper surface of the PCB <b>1101</b>. The plurality of light sources <b>1105</b> may be driven by the LED driving apparatus <b>110</b>, <b>210</b>, or <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

<figref idref="DRAWINGS">FIG. 18</figref> is a view illustrating an example of disposition of light sources in the direct type backlight unit.

A direct type backlight unit <b>1200</b> according to the exemplary embodiment may include a plurality of light sources <b>1205</b> arranged on a board <b>1201</b>.

The arrangement structure of the light sources <b>1205</b> is a matrix structure in which the light sources <b>1205</b> are arranged in rows and columns, and here, the rows and columns have a zigzag form. This is a structure in which a second matrix having the same form as that of a first matrix is disposed within the first matrix in which the plurality of light sources <b>1205</b> are arranged in rows and columns in straight lines, which may be understood as that each light source <b>1205</b> of the second matrix is positioned within a quadrangle formed by four adjacent light sources <b>1205</b> included in the first matrix.

However, in the direct type backlight unit <b>1200</b> according to the exemplary embodiment illustrated in <figref idref="DRAWINGS">FIG. 18</figref>, in order to enhance uniformity of brightness and light efficiency, if necessary, the first and second matrices may have different disposition structures and intervals. Also, in addition to the method of disposing the plurality of light sources, distances S<b>1</b> and S<b>2</b> between adjacent light sources may be optimized to secure uniformity of brightness.

In this manner, since the rows and columns of the light sources <b>1205</b> are disposed in a zigzag manner, rather than being disposed in straight lines, the number of light sources <b>1205</b> may be reduced by about 15% to 25% in comparison with a backlight unit having the same light emitting area.

<figref idref="DRAWINGS">FIG. 19</figref> is a view illustrating another embodiment of a direct type backlight unit.

Referring to <figref idref="DRAWINGS">FIG. 19</figref>, a backlight unit <b>1300</b> according to an exemplary embodiment may include an optical sheet <b>1320</b> and a light source module <b>1310</b> arranged below the optical sheet <b>1320</b>.

The optical sheet <b>1320</b> may include a diffusion sheet <b>1321</b>, a light collecting sheet <b>1322</b>, a protective sheet <b>1323</b>, and the like. A configuration and an arrangement order of the sheets <b>1321</b> to <b>1323</b> included in the optical sheet <b>1320</b> are not limited to those illustrated in <figref idref="DRAWINGS">FIG. 19</figref>, and may be variously modified.

The light source module <b>1310</b> may include a circuit board <b>1311</b> and a plurality of light source units <b>1312</b> mounted on the circuit board <b>1311</b>. The plurality of light source units <b>1312</b> may be driven by the LED driving apparatus <b>110</b>, <b>210</b>, or <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>, and optical elements adjusting a path of light emitted from the light source may be disposed on the light sources.

The optical elements may adjust a beam angle of light through refraction, and in particular, a wide beam angle lens diffusing light from the light source units <b>1312</b> to a wide region may be mainly used as the optical elements. Since the light source units <b>1312</b> with the optical elements attached thereto may have wider light distribution (and thus, when the light source module is used in a backlight, a planar lighting, and the like), the number of light sources <b>1312</b> per unit area may be reduced.

<figref idref="DRAWINGS">FIG. 20</figref> is an exploded view illustrating the light source unit <b>1312</b> illustrated in <figref idref="DRAWINGS">FIG. 19</figref>.

Referring to <figref idref="DRAWINGS">FIG. 20</figref>, each of the plurality of light source units <b>1312</b> may include a light source <b>1314</b> including a light emitting device package <b>100</b>, <b>200</b>, <b>300</b>, or <b>400</b> and an optical element <b>1313</b>. The optical element <b>1313</b> may include a bottom surface <b>1313</b><i>a </i>disposed on the light source <b>1314</b>, an incident surface <b>1313</b><i>b </i>to which light from the light source <b>1314</b> is incident, and an output surface <b>1313</b><i>c </i>from which light is emitted outwardly.

The bottom surface <b>1313</b><i>a </i>may have a recess portion <b>1313</b><i>d </i>formed in the center through which an optical axis Z of the light source <b>1314</b> passes, and may be depressed in a direction toward the output surface <b>1313</b><i>c</i>. A surface of the recess portion <b>1313</b><i>d </i>may be defined as the incident surface <b>1313</b><i>b </i>to which light from the light source <b>1314</b> is incident. That is, the incident surface <b>1313</b><i>b </i>may form the surface of the recess portion <b>1313</b><i>d. </i>

A central region of the bottom surface <b>1313</b><i>a </i>connected to the incident surface <b>1313</b><i>b </i>partially protrudes to the light source <b>1314</b>, thereby forming an overall non-flat structure. Unlike a general structure in which the entirety of the bottom surface <b>1313</b><i>a </i>is flat, the bottom surface <b>1313</b><i>a </i>has a structure in which portions thereof protrude along the circumference of the recess portion <b>1313</b><i>d</i>. A plurality of support portions <b>1313</b><i>f </i>may be provided on the bottom surface <b>1313</b><i>a </i>in order to fixedly support the optical element <b>1313</b> when the optical element <b>1313</b> is mounted on the circuit board <b>1311</b>.

The output surface <b>1313</b><i>c </i>protrudes to have a dome shape in an upward direction (a light output direction) from the edge connected to the bottom surface <b>1313</b><i>a</i>, and the center of the output surface <b>1313</b><i>c </i>through which the optical axis Z passes is depressed to be concave toward the recess portion <b>1313</b><i>d</i>, having a point of inflection.

A plurality of prominences and depressions <b>1313</b><i>e </i>may be periodically arranged in a direction from the optical axis Z toward the edge. The horizontal cross-section of each of the plurality of prominences and depressions <b>1313</b><i>e </i>may be an annular shape, and may form concentric circles centered on the optical axis Z. The plurality of prominences and depressions <b>1313</b><i>e </i>may be periodically arranged to spread out radially along the output surface <b>1313</b><i>c </i>from the optical axis Z.

The plurality of prominences and depressions <b>1313</b><i>e </i>may be spaced apart by a predetermined period (pitch) P to form patterns. In this case, the period P between the plurality of prominences and depressions <b>1313</b><i>e </i>may range, for example, from 0.01 mm to 0.04 mm. The plurality of prominences and depressions <b>1313</b><i>e </i>may offset a performance gap of optical elements arising from a microscopic machining error generated in a process of fabricating the optical elements, thereby enhancing uniformity of light distribution.

<figref idref="DRAWINGS">FIG. 21</figref> is a view illustrating another embodiment of a direct type backlight unit.

Referring to <figref idref="DRAWINGS">FIG. 21</figref>, a backlight unit <b>1400</b> includes a light source <b>1405</b> mounted on a circuit board <b>1401</b> and at least one optical sheet <b>1406</b> disposed thereabove. The light source <b>1405</b> may be driven by the LED driving apparatus <b>110</b>, <b>210</b>, or <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

The circuit board <b>1401</b> employed in the exemplary embodiment may have a first planar portion <b>1401</b><i>a </i>corresponding to a main region, a sloped portion <b>1401</b><i>b </i>disposed around the first planar portion <b>1401</b><i>a </i>and bent in at least a portion thereto, and a second planar portion <b>1401</b><i>c </i>disposed on the edge of the circuit board <b>1501</b>, namely, an outer side of the sloped portion <b>1401</b><i>b</i>. The light sources <b>1405</b> are arranged at a first interval d<b>1</b> on the first planar portion <b>1401</b><i>a</i>, and one or more light sources <b>1405</b> may be arranged at a second interval d<b>2</b> on the sloped portion <b>1401</b><i>b</i>. The first interval d<b>1</b> may be equal to the second interval d<b>2</b>. A width of the sloped portion <b>1401</b><i>b </i>(or a length in the cross-section) may be smaller than that of the first planar portion <b>1401</b><i>a </i>and may be larger than a width of the second planar portion <b>1401</b><i>c</i>. Also, if necessary, at least one light source <b>1405</b> may be arranged on the second planar portion <b>1401</b><i>c. </i>

A slope of the sloped portion <b>1401</b><i>b </i>may be appropriately adjusted within a range from 0 to 90 degrees with respect to the first planar portion <b>1401</b><i>a</i>, and with this structure, the circuit board <b>1401</b> may maintain uniform brightness even in the vicinity of the edge of the optical sheet <b>1406</b>.

In backlight units <b>1500</b>, <b>1600</b>, and <b>1700</b> in <figref idref="DRAWINGS">FIG. 22</figref> through <figref idref="DRAWINGS">FIG. 24</figref>, wavelength conversion units <b>1550</b>, <b>1650</b>, and <b>1750</b> are disposed outside of light sources <b>1505</b>, <b>1605</b>, and <b>1705</b>, rather than being disposed in the light sources <b>1505</b>, <b>1605</b>, and <b>1705</b>, to convert light, respectively.

Referring to <figref idref="DRAWINGS">FIG. 22</figref>, the backlight unit <b>1500</b> is a direct type backlight unit including the wavelength conversion unit <b>1550</b>, a light source module <b>1510</b> arranged below the wavelength conversion unit <b>1550</b>, and a bottom case <b>1560</b> accommodating the light source module <b>1510</b>. Also, the light source module <b>1510</b> may include a PCB <b>1501</b> and a plurality of light sources <b>1505</b> mounted on an upper surface of the PCB <b>1501</b>.

In the backlight unit <b>1500</b> according to the exemplary embodiment of <figref idref="DRAWINGS">FIG. 22</figref>, the wavelength conversion unit <b>1550</b> may be disposed above the bottom case <b>1560</b>. Thus, at least a partial amount of light emitted from the light source module <b>1510</b> may be wavelength-converted by the wavelength conversion unit <b>1550</b>. The wavelength conversion unit <b>1550</b> may be manufactured as a separate film and applied to the backlight unit <b>1500</b> in a film form, or alternatively, the wavelength conversion unit <b>1550</b> may be integrally combined with a light diffuser (not shown) so as to be provided.

Referring to <figref idref="DRAWINGS">FIGS. 23 and 24</figref>, backlight units <b>1600</b> and <b>1700</b> are edge type backlight units respectively including wavelength conversion units <b>1650</b> and <b>1750</b>, light guide plates <b>1640</b> and <b>1740</b>, and reflective units <b>1620</b> and <b>1720</b> and light sources <b>1605</b> and <b>1705</b> disposed on one side of the light guide plates <b>1640</b> and <b>1740</b>.

Light emitted from the light sources <b>1605</b> and <b>1705</b> may be guided to the interior of the light guide plates <b>1640</b> and <b>1740</b> by the reflective units <b>1620</b> and <b>1720</b>, respectively. In the backlight unit <b>1600</b> of <figref idref="DRAWINGS">FIG. 23</figref>, the wavelength conversion unit <b>1650</b> may be disposed between the light guide plate <b>1640</b> and the light source <b>1605</b>. In the backlight unit <b>1700</b> of <figref idref="DRAWINGS">FIG. 24</figref>, the wavelength conversion unit <b>1750</b> may be disposed on a light emitting surface of the light guide plate <b>1740</b>.

In <figref idref="DRAWINGS">FIG. 22</figref> through <figref idref="DRAWINGS">FIG. 24</figref>, the wavelength conversion units <b>1550</b>, <b>1650</b>, and <b>1750</b> may include a general phosphor. In particular, in the case of using a quantum dot phosphor, the structures of wavelength conversion units <b>1550</b>, <b>1650</b>, and <b>1750</b> illustrated in <figref idref="DRAWINGS">FIG. 22</figref> through <figref idref="DRAWINGS">FIG. 24</figref> may be utilized in the backlight units <b>1500</b>, <b>1600</b>, and <b>1700</b> in order to compensate for the vulnerability of the quantum dot phosphor to heat or moisture from a light source.

<figref idref="DRAWINGS">FIG. 25</figref> is a schematic, exploded perspective view of a display apparatus including the LED driving apparatus according to an exemplary embodiment of the present inventive concept.

Referring to <figref idref="DRAWINGS">FIG. 25</figref>, a display apparatus <b>2000</b> may include a backlight unit <b>2100</b>, an optical sheet <b>2200</b>, and an image display panel <b>2300</b> such as a liquid crystal panel.

The backlight unit <b>2100</b> may include a bottom case <b>2110</b>, a reflective plate <b>2120</b>, a light guide plate <b>2140</b>, and a light source module <b>2130</b> provided on at least one side of the light guide plate <b>2140</b>. The light source module <b>2130</b> may include a PCB <b>2131</b> and light sources <b>2132</b>. In particular, the light sources <b>2132</b> may be driven by the LED driving apparatus <b>110</b>, <b>210</b>, or <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

The optical sheet <b>2200</b> may be disposed between the light guide plate <b>2140</b> and the image display panel <b>2300</b> and may include various types of sheets such as a diffusion sheet, a prism sheet, and a protective sheet.

The image display panel <b>2300</b> may display an image using light output from the optical sheet <b>2200</b>. The image display panel <b>2300</b> may include an array substrate <b>2320</b>, a liquid crystal layer <b>2330</b>, and a color filter substrate <b>2340</b>. The array substrate <b>2320</b> may include pixel electrodes disposed in a matrix form, thin film transistors (TFTs) applying a driving voltage to the pixel electrodes, and signal lines operating the TFTs. The color filter substrate <b>2340</b> may include a transparent substrate, a color filter, and a common electrode. The color filter may include filters allowing light having a particular wavelength, included in white light emitted from the backlight unit <b>2100</b>, to selectively pass therethrough. Liquid crystals contained in the liquid crystal layer <b>2330</b> are rearranged by an electric field applied between the pixel electrodes and the common electrode, and thereby light transmittance is adjusted. The light with transmittance thereof adjusted may pass through the color filter of the color filter substrate <b>2340</b>, thus displaying an image. The image display panel <b>2300</b> may further include a driving circuit unit processing an image signal, or the like.

The display apparatus <b>2000</b> according to certain exemplary embodiments uses the light sources <b>2132</b> emitting blue light, green light, and red light having a relatively small FWHM. Thus, emitted light, after passing through the color filter substrate <b>2340</b>, may implement blue, green, and red having a high level of color purity.

<figref idref="DRAWINGS">FIG. 26</figref> through <figref idref="DRAWINGS">FIG. 29</figref> are views each illustrating a lighting apparatus according to other exemplary embodiments of the present inventive concept.

Referring to <figref idref="DRAWINGS">FIG. 26</figref>, a planar type lighting apparatus <b>4000</b> may include a light source module <b>4010</b>, a power supply device <b>4020</b>, and a housing <b>4030</b>. According to an exemplary embodiment of the present inventive concept, the light source module <b>4010</b> may include a light emitting device array as a light source, and the power supply device <b>4020</b> may include a light emitting device driving unit.

The light source module <b>4010</b> may include a light emitting device array and may be formed to have an overall planar shape. According to an exemplary embodiment of the present inventive concept, the light emitting device array may include a light emitting device and a controller storing driving information of the light emitting device. The light emitting device array may include a plurality of light emitting device packages connected to each other in series or in parallel.

The power supply device <b>4020</b> may be configured to supply power to the light source module <b>4010</b>, and may include the LED driving apparatuses <b>110</b>, <b>210</b>, and <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>. The housing <b>4030</b> may have an accommodation space accommodating the light source module <b>4010</b> and the power supply device <b>4020</b> therein and have a hexahedral shape with one side thereof open, but the shape of the housing <b>4030</b> is not limited thereto. The light source module <b>4010</b> may be disposed to emit light to the open side of the housing <b>4030</b>.

<figref idref="DRAWINGS">FIG. 27</figref> is an exploded perspective view schematically illustrating a bar type lamp as a lighting apparatus according to an exemplary embodiment of the present inventive concept.

In detail, a lighting apparatus <b>4100</b> includes a heat sink <b>4110</b>, a cover <b>4120</b>, a light source module <b>4130</b>, a first socket <b>4140</b>, and a second socket <b>4150</b>. A plurality of heat sink fins <b>4111</b> and <b>4112</b> may be formed in a concavo-convex pattern on an internal and/or external surface of the heat sink <b>4110</b>, and the heat sink fins <b>4111</b> and <b>4112</b> may be designed to have various shapes and intervals (spaces) therebetween. A support <b>4113</b> having a protruded shape may be formed on an inner side of the heat sink <b>4110</b>. The light source module <b>4130</b> may be fixed to the support <b>4113</b>. Stoppage protrusions <b>4114</b> may be formed on both ends of the heat sink <b>4110</b>.

The stoppage recesses <b>4121</b> may be formed in the cover <b>4120</b>, and the stoppage protrusions <b>4114</b> of the heat sink <b>4110</b> may be coupled to the stoppage recesses <b>4121</b>. The positions of the stoppage recesses <b>4121</b> and the stoppage protrusions <b>4114</b> may be interchanged.

The light source module <b>4130</b> may include a light emitting device array. The light source module <b>4130</b> may include a PCB <b>4131</b>, a light source <b>4132</b>, and a controller <b>4133</b>. As described above, the controller <b>4133</b> may store driving information of the light source <b>4132</b>. Circuit wirings are formed on the PCB <b>4131</b> to operate the light source <b>4132</b>. Also, components for operating the light source <b>4132</b> may be provided. For example, the LED driving apparatuses <b>110</b>, <b>210</b>, and <b>310</b> described with reference to FIG. <b>1</b> through <figref idref="DRAWINGS">FIG. 6</figref> may be implemented in the PCB <b>4131</b>, and the controller <b>4133</b> may perform functions of the controller IC <b>112</b>, <b>212</b>, and <b>312</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

The first and second sockets <b>4140</b> and <b>4150</b>, a pair of sockets, are respectively coupled to opposing ends of the cylindrical cover unit including the heat sink <b>4110</b> and the cover <b>4120</b>. For example, the first socket <b>4140</b> may include electrode terminals <b>4141</b> and a power source device <b>4142</b>, and dummy terminals <b>4151</b> may be disposed on the second socket <b>4150</b>. Also, an optical sensor and/or a communications module may be installed in either the first socket <b>4140</b> or the second socket <b>4150</b>. For example, the optical sensor and/or the communications module may be installed in the second socket <b>4150</b> in which the dummy terminals <b>4151</b> are disposed. In another example, the optical sensor and/or the communications module may be installed in the first socket <b>4140</b> in which the electrode terminals <b>4141</b> are disposed.

<figref idref="DRAWINGS">FIG. 28</figref> is an exploded perspective view schematically illustrating a bulb type lamp as a lighting apparatus according to an exemplary embodiment of the present inventive concept.

In detail, a lighting apparatus <b>4200</b> may include a socket <b>4210</b>, a power source unit <b>4220</b>, a heat sink <b>4230</b>, a light source module <b>4240</b>, and an optical unit <b>4250</b>. According to an exemplary embodiment of the present inventive concept, the light source module <b>4240</b> may include a light emitting device array, and the power source unit <b>4220</b> may be driven by the LED driving apparatuses <b>110</b>, <b>210</b>, and <b>310</b> described with reference to <figref idref="DRAWINGS">FIG. 1</figref> through <figref idref="DRAWINGS">FIG. 6</figref>.

The socket <b>4210</b> may be configured to be replaced with an existing lighting apparatus. Power supplied to the lighting apparatus <b>4200</b> may be applied through the socket <b>4210</b>. As illustrated, the power source unit <b>4220</b> may include a first power source unit <b>4221</b> and a second power source unit <b>4222</b>. The first power source unit <b>4221</b> and the second power source unit <b>4222</b> may be assembled to form the power source unit <b>4220</b>. The heat sink <b>4230</b> may include an internal heat sink <b>4231</b> and an external heat sink <b>4232</b>. The internal heat sink <b>4231</b> may be directly connected to the light source module <b>4240</b> and/or the power source unit <b>4220</b> to transmit heat to the external heat sink <b>4232</b>. The optical unit <b>4250</b> may include an internal optical unit (not shown) and an external optical unit (not shown) and may be configured to evenly distribute light emitted from the light source module <b>4240</b>.

The light source module <b>4240</b> may emit light to the optical unit <b>4250</b> upon receiving power from the power source unit <b>4220</b>. The light source module <b>4240</b> may include one or more light emitting devices <b>4241</b>, a circuit board <b>4242</b>, and a controller <b>4243</b>. The controller <b>4243</b> may store driving information of the light emitting devices <b>4241</b>.

<figref idref="DRAWINGS">FIG. 29</figref> is an exploded perspective view schematically illustrating a lamp, including a communications module, as a lighting apparatus, according to an exemplary embodiment of the present inventive concept.

In detail, a lighting apparatus <b>4300</b> according to the present exemplary embodiment is different from the lighting apparatus <b>4200</b> illustrated in <figref idref="DRAWINGS">FIG. 28</figref>, in that a reflective plate <b>4310</b> is provided above the light source module <b>4240</b>, and here, the reflective plate <b>4310</b> serves to allow light from the light source to spread evenly toward the lateral and back sides thereof, and thereby glare may be reduced.

A communications module <b>4320</b> may be mounted on an upper portion of the reflective plate <b>4310</b>, and home network communication may be realized through the communications module <b>4320</b>. For example, the communications module <b>4320</b> may be a wireless communications module using ZigBee, Wi-Fi, or light fidelity (Li-Fi), and may control lighting installed within or outside of a household, such as turning on or off a lighting apparatus, adjusting brightness of a lighting apparatus, and the like, through a smartphone or a wireless controller. Also, home appliances or an automobile system within or outside of a household, such as a TV, a refrigerator, an air-conditioner, a door lock, or automobiles, and the like, may be controlled through a Li-Fi communications module using visible wavelengths of the lighting apparatus installed within or outside of the household.

The reflective plate <b>4310</b> and the communications module <b>4320</b> may be covered by a cover unit <b>4330</b>.

<figref idref="DRAWINGS">FIG. 30</figref> through <figref idref="DRAWINGS">FIG. 32</figref> are schematic views, each illustrating a network system including a light driving apparatus according to an exemplary embodiment of the present inventive concept.

<figref idref="DRAWINGS">FIG. 30</figref> is a view schematically illustrating an indoor lighting control network system. A network system <b>5000</b> may be a complex smart lighting-network system combining lighting technology using a light emitting device such as an LED, or the like, Internet of Things (IoT) technology, wireless communications technology, and the like. The network system <b>5000</b> may be realized using various lighting apparatuses and wired/wireless communications devices, and may be realized by a sensor, a controller, a communications unit, software for network control and maintenance, and the like.

The network system <b>5000</b> may be applied even to an open space such as a park or a street, as well as to a closed space such as a home or an office. The network system <b>5000</b> may be realized on the basis of the IoT environment in order to collect and process a variety of information and provide the same to users. Here, an LED lamp <b>5200</b> included in the network system <b>5000</b> may serve not only to receive information regarding a surrounding environment from a gateway <b>5100</b> and control lighting of the LED lamp <b>5200</b> itself, but also to check and control operational states of other devices <b>5300</b> to <b>5800</b> included in the IoT environment on the basis of a function such as visible light communications, or the like, of the LED lamp <b>5200</b>.

Referring to <figref idref="DRAWINGS">FIG. 30</figref>, the network system <b>5000</b> may include the gateway <b>5100</b> processing data transmitted and received according to different communications protocols, the LED lamp <b>5200</b> connected to be available for communicating with the gateway <b>5100</b> and including an LED light emitting device, and a plurality of devices <b>5300</b> to <b>5800</b> connected to be available for communicating with the gateway <b>5100</b> according to various wireless communications schemes. In order to realize the network system <b>5000</b> on the basis of the IoT environment, each of the devices <b>5300</b> to <b>5800</b>, as well as the LED lamp <b>5200</b>, may include at least one communications module. In an exemplary embodiment, the LED lamp <b>5200</b> may be connected to be available for communicating with the gateway <b>5100</b> according to wireless communication protocols such as Wi-Fi, ZigBee, or Li-Fi, and to this end, the LED lamp <b>5200</b> may include at least one communications module <b>5210</b> for a lamp.

As mentioned above, the network system <b>5000</b> may be applied even to an open space such as a park or a street, as well as to a closed space such as a home or an office. When the network system <b>5000</b> is applied to a home, the plurality of devices <b>5300</b> to <b>5800</b> included in the network system and connected to be available for communicating with the gateway <b>5100</b> on the basis of the IoT technology may include a home appliance <b>5300</b>, a digital door lock <b>5400</b>, a garage door lock <b>5500</b>, a light switch <b>5600</b> installed on a wall, or the like, a router <b>5700</b> for relaying a wireless communication network, and a mobile device <b>5800</b> such as a smartphone, a tablet PC, or a laptop computer.

In the network system <b>5000</b>, the LED lamp <b>5200</b> may check operational states of various devices <b>5300</b> to <b>5800</b> using the wireless communications network (ZigBee, Wi-Fi, LI-Fi, etc.) installed in a household or automatically control illumination of the LED lamp <b>5200</b> itself according to a surrounding environment or situation. Also, the devices <b>5300</b> to <b>5800</b> included in the network system <b>5000</b> may be controlled using Li-Fi communications using visible light emitted from the LED lamp <b>5200</b>.

First, the LED lamp <b>5200</b> may automatically adjust illumination of the LED lamp <b>5200</b> on the basis of information of a surrounding environment transmitted from the gateway <b>5100</b> through the communications module <b>5210</b> for a lamp or information of a surrounding environment collected from a sensor installed in the LED lamp <b>5200</b>. For example, brightness of illumination of the LED lamp <b>5200</b> may be automatically adjusted according to types of programs broadcast on the TV <b>5310</b> or brightness of a screen. To this end, the LED lamp <b>5200</b> may receive operation information of the TV <b>5310</b> from the communications module <b>5210</b> for a lamp connected to the gateway <b>5100</b>. The communications module <b>5210</b> for a lamp may be integrally modularized with a sensor and/or a controller included in the LED lamp <b>5200</b>.

For example, when a TV program broadcast is a drama, a color temperature of illumination may be decreased to be 12000K or lower, for example, to 5000K, and a color tone may be adjusted according to preset values, and thereby a cozy atmosphere is presented. Conversely, when a program value is a comedy program, the network system <b>5000</b> may be configured so that a color temperature of illumination is increased to 5000K or higher according to a preset value, and illumination is adjusted to white illumination based on a blue color.

Also, when no one is at home, and a predetermined time has lapsed after the digital door lock <b>5400</b> is locked, all of the turned-on LED lamps <b>5200</b> are turned off to prevent a waste of electricity. Also, when a security mode is set through the mobile device <b>5800</b>, or the like, and the digital door lock <b>5400</b> is locked with no one at home, the LED lamp <b>5200</b> may be maintained in a turned-on state.

An operation of the LED lamp <b>5200</b> may be controlled according to surrounding environments collected through various sensors connected to the network system <b>5000</b>. For example, when the network system <b>5000</b> is realized in a building, a lighting, a position sensor, and a communications module are combined in the building, and position information of people in the building is collected and the lighting is turned on or turned off, or the collected information may be provided in real time to effectively manage facilities or effectively utilize an idle space. In general, a lighting apparatus such as the LED lamp <b>5200</b> is disposed in almost every space of each floor of a building, and thus, various types of information of the building may be collected through a sensor integrally provided with the LED lamp <b>5200</b> and used for managing facilities and utilizing an idle space.

Meanwhile, the LED lamp <b>5200</b> may be combined with an image sensor, a storage device, and the communications module <b>5210</b> for a lamp, to be utilized as a device for maintaining building security, or sensing and coping with an emergency situation. For example, when a smoke or temperature sensor, or the like, is attached to the LED lamp <b>5200</b>, a fire may be promptly sensed to minimize damage. Also, brightness of lighting may be adjusted in consideration of outside weather or an amount of sunshine, thereby saving energy and providing an agreeable illumination environment.

As described above, the network system <b>5000</b> may also be applied to an open space such as a street or a park, as well as to a closed space such as a home, an office, or a building. When the network system <b>5000</b> is intended to be applied to an open space without a physical limitation, it may be difficult to realize the network system <b>5000</b> due to a limitation in a distance of wireless communications or communications interference due to various obstacles. In this case, a sensor, a communications module, and the like, may be installed in each lighting fixture, and each lighting fixture may be used as an information collecting means or a communications relay means, whereby the network system <b>5000</b> may be more effectively realized in an open environment. This will hereinafter be described with reference to <figref idref="DRAWINGS">FIG. 31</figref>.

<figref idref="DRAWINGS">FIG. 31</figref> is a view illustrating an embodiment of a network system <b>6000</b> applied to an open space. Referring to <figref idref="DRAWINGS">FIG. 31</figref>, a network system <b>6000</b> according to the present exemplary embodiment may include a communications connection device <b>6100</b>, a plurality of lighting fixtures <b>6200</b> and <b>6300</b> installed at every predetermined interval and connected to be available for communicating with the communications connection device <b>6100</b>, a server <b>6400</b>, a computer <b>6500</b> managing the server <b>6400</b>, a communications base station <b>6600</b>, a communications network <b>6700</b>, a mobile device <b>6800</b>, and the like.

Each of the plurality of lighting fixtures <b>6200</b> and <b>6300</b> installed in an open outer space such as a street or a park may include smart engines <b>6210</b> and <b>6310</b>, respectively. The smart engines <b>6210</b> and <b>6310</b> may include a light emitting device, a driver of the light emitting device, a sensor collecting information of a surrounding environment, a communications module, and the like. The smart engines <b>6210</b> and <b>6310</b> may communicate with other neighboring equipment by means of the communications module according to communications protocols such as Wi-Fi, ZigBee, and Li-Fi.

For example, one smart engine <b>6210</b> may be connected to communicate with another smart engine <b>6310</b>. Here, a Wi-Fi extending technique (Wi-Fi mesh) may be applied to communications between the smart engines <b>6210</b> and <b>6310</b>. The at least one smart engine <b>6210</b> may be connected to the communications connection device <b>6100</b> connected to the communications network <b>6700</b> by wired/wireless communications. In order to increase communication efficiency, some smart engines <b>6210</b> and <b>6310</b> may be grouped and connected to the single communications connection device <b>6100</b>.

The communications connection device <b>6100</b> may be an access point (AP) available for wired/wireless communications, which may relay communications between the communications network <b>6700</b> and other equipment. The communications connection device <b>6100</b> may be connected to the communications network <b>6700</b> in either a wired manner or a wireless manner, and for example, the communications connection device <b>6100</b> may be mechanically received in any one of the lighting fixtures <b>6200</b> and <b>6300</b>.

The communications connection device <b>6100</b> may be connected to the mobile device <b>6800</b> through a communications protocol such as Wi-Fi, or the like. A user of the mobile device <b>6800</b> may receive surrounding environment information collected by the plurality of smart engines <b>6210</b> and <b>6310</b> through the communications connection device <b>6100</b> connected to the smart engine <b>6210</b> of the lighting fixture <b>6200</b> adjacent to the mobile device <b>6800</b>. The surrounding environment information may include nearby traffic information, weather information, and the like. The mobile device <b>6800</b> may be connected to the communications network <b>6700</b> according to a wireless cellular communications scheme such as 3G or 4G through the communications base station <b>6600</b>.

Meanwhile, the server <b>6400</b> connected to the communications network <b>6700</b> may receive information collected by the smart engines <b>6210</b> and <b>6310</b> respectively installed in the lighting fixtures <b>6200</b> and <b>6300</b> and monitor an operational state, or the like, of each of the lighting fixtures <b>6200</b> and <b>6300</b>. In order to manage the lighting fixtures <b>6200</b> and <b>6300</b> on the basis of the monitoring results of the operational states of the lighting fixtures <b>6200</b> and <b>6300</b>, the server <b>6400</b> may be connected to the computer <b>6500</b> providing a management system. The computer <b>6500</b> may execute software, or the like, capable of monitoring and managing operational states of the lighting fixtures <b>6200</b> and <b>6300</b>, specifically, the smart engines <b>6210</b> and <b>6310</b>.

In order to transmit information collected by the smart engines <b>6210</b> and <b>6310</b> to the mobile device <b>6800</b> of the user, various communications schemes may be applied. Referring to <figref idref="DRAWINGS">FIG. 31</figref>, information collected by the smart engines <b>6210</b> and <b>6310</b> may be transmitted to the mobile device <b>6100</b> through the communications connection device <b>6100</b> connected to the smart engines <b>6210</b> and <b>6310</b>, or the smart engines <b>6210</b> and <b>6310</b> and the mobile device <b>6800</b> may be connected to directly communicate with each other. The smart engines <b>6210</b> and <b>6310</b> and the mobile device <b>6800</b> may directly communicate with each other by visible light communications (Li-Fi). This will hereinafter be described with reference to <figref idref="DRAWINGS">FIG. 32</figref>.

<figref idref="DRAWINGS">FIG. 32</figref> is a block diagram illustrating a communications operation between the smart engine <b>6210</b> of the lighting fixture <b>6200</b> and the mobile device <b>6800</b> according to visible light communications. Referring to <figref idref="DRAWINGS">FIG. 32</figref>, the smart engine <b>6210</b> may include a signal processing unit <b>6211</b>, a control unit <b>6212</b>, an LED driver <b>6213</b>, a light source unit <b>6214</b>, a sensor <b>6215</b>, and the like. The mobile device <b>6800</b> connected to the smart engine <b>6210</b> by visible light communications may include a control unit <b>6801</b>, a light receiving unit <b>6802</b>, a signal processing unit <b>6803</b>, a memory <b>6804</b>, an input/output unit <b>6805</b>, and the like.

The visible light communications (VLC) technology (or light fidelity (Li-Fi)) is a wireless communications technology transferring information wirelessly by using light having a visible light wavelength band recognizable to the naked eye. The visible light communications technology is distinguished from the existing wired optical communications technology and the infrared data association (IrDA) in that it uses light having a visible light wavelength band, namely, a particular visible light frequency from the light emitting device package according to the exemplary embodiment described above and is distinguished from the existing wired optical communications technology in that a communications environment is based on a wireless scheme. Also, unlike RF wireless communications, the VLC technology (or Li-Fi) has excellent convenience because it can be used without being regulated or authorized in the aspect of frequency usage, and VLC technology (or Li-Fi) has a distinction of having excellent physical security and a user's verification of a communication link with his or her own eyes. Most of all, VLC technology (or Li-Fi) is differentiated in that it has features as a convergence technology that obtains both a unique purpose as a light source and a communications function.

Referring to <figref idref="DRAWINGS">FIG. 32</figref>, the signal processing unit <b>6211</b> of the smart engine <b>6210</b> may process data intended to be transmitted and received by VLC. In an exemplary embodiment, the signal processing unit <b>6211</b> may process information collected by the sensor <b>6215</b> into data and transmit the processed data to the control unit <b>6212</b>. The control unit <b>6212</b> may control operations of the signal processing unit <b>6211</b>, the LED driver <b>6213</b>, and the like, and in particular, the control unit <b>6212</b> may control an operation of the LED driver <b>6213</b> on the basis of data transmitted from the signal processing unit <b>6211</b>. The LED driver <b>6213</b> emits the light source unit <b>6214</b> according to a control signal transmitted from the control unit <b>6212</b>, thereby transmitting data to the mobile device <b>6800</b>.

The mobile device <b>6800</b> may include the light receiving unit <b>6802</b> for recognizing visible light including data, in addition to the control unit <b>6801</b>, the memory <b>6804</b> storing data, the input/output unit <b>6805</b> including a display, a touchscreen, an audio output unit, and the like, and the signal processing unit <b>6803</b>. The light receiving unit <b>6802</b> may sense visible light and convert the sensed visible light into an electrical signal, and the signal processing unit <b>6803</b> may decode data included in the electrical signal converted by the light receiving unit <b>6802</b>. The control unit <b>6801</b> may store the data decoded by the signal processing unit <b>6803</b> in the memory <b>6804</b> or may output the decoded data through the input/output unit <b>6805</b> to allow the user to recognize the data.

As set forth above, according to exemplary embodiments of the present inventive concept, an LED driving apparatus and a lighting apparatus in which a converter circuit may be omitted because an LED array is directly connected to a rectifier circuit to emit light, and in particular, a portion of a current flowing in the LED array may be dispersed to drive a high output LED, may be provided.

While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the invention as defined by the appended claims.